TIN Compliance Glossary: B-Notice, CP2100, 972CG, 147C and More

1099 compliance

The everyday name for the whole process this site covers: collecting W-9s, verifying TINs, filing accurate information returns, and handling the notices that follow. Vendors call it TIN compliance; tax departments call it information-reporting compliance. Same work.

TIN (taxpayer identification number)

The nine-digit number the IRS uses to identify a taxpayer on an information return: a Social Security number, an ITIN or an EIN. The IRS matches the TIN together with the payee's name, so a real number with the wrong name still fails.

SSN (Social Security number)

The TIN for individuals, issued by the Social Security Administration. On a W-9, an SSN must be paired with the individual's own name on line 1, even if the individual operates a business.

ITIN (Individual Taxpayer Identification Number)

A nine-digit number the IRS issues to individuals who need a TIN but are not eligible for an SSN. "The ITIN will be in the format of an SSN and begin with the number '9'. The fourth and fifth numbers will range from: 50-65, 70-88, 90-92, 94-99" (IRM 3.21.263.2(9)-(10), Aug. 28, 2025). It is "only for federal tax purposes" and does not qualify the holder to work in the United States (IRM 3.21.263.2(11)-(12)). An ITIN not used on a 1040-series return for three consecutive years expires on December 31 of the third year, with no CP 48 notice (IRM 3.21.263.2.1, 3.21.263.8.2(4)); an expired ITIN stays on DM-1 with its name control, and only a revoked ITIN is removed (IRM 3.21.263.2.1(6)). Since December 2003 it is issued by CP 565, not by card. See ITINs on W-9s and 1099s.

EIN (Employer Identification Number)

The TIN for businesses, trusts, estates and other entities, issued by the IRS. It matches only against the legal name the IRS assigned it to, shown on the CP 575 notice or a Letter 147C.

Name control

The four characters the IRS derives from a payee's name to perform the match. It is why minor punctuation differences usually still match and a different entity name never does.

Form W-9

The form a U.S. payee uses to give a payer its name, TIN and tax classification, with a certification under penalties of perjury. The payer keeps it; it is not sent to the IRS.

Form W-8 (W-8BEN, W-8BEN-E)

The equivalent of a W-9 for foreign payees. A foreign payee is generally outside 1099 reporting and backup withholding and instead falls under chapter 3 withholding and Form 1042-S.

Solicitation

A request to a payee to furnish a correct TIN. Treas. Reg. 301.6724-1 sets a schedule (initial, first annual, second annual) that a payer must follow for a missing-TIN penalty to be waived for reasonable cause.

TIN Matching Program

The free IRS e-Services program that tells an enrolled payer whether a name/TIN pair matches IRS records, returning a code from 0 to 8. Interactive requests take 25 pairs; bulk files up to 100,000 with results in 24 hours.

CP2100 / CP2100A

The notice the IRS sends a payer listing the information returns whose name/TIN pairs didn't match (or had no TIN). CP2100A is the version for fewer than 50 errors. It starts the B-Notice clock.

B-Notice

The letter a payer must send a payee within 15 business days of a CP2100, asking for a corrected TIN. A First B-Notice encloses a W-9; a Second B-Notice (same account within three years) requires an SSA card copy or Letter 147C instead.

Backup withholding

The 24% a payer must withhold from reportable payments when a payee's TIN is missing, IRS-notified as incorrect, or otherwise flagged. It is deposited with the IRS, reported on Form 945, and credited to the payee on their return.

Form 945

The annual return for federal income tax withheld from nonpayroll payments, including backup withholding. Due January 31 (February 10 if all deposits were timely).

Letter 147C

An IRS letter confirming the legal name and EIN on file for a business, requested by calling the Business & Specialty Tax Line. It is what a payee provides in response to a Second B-Notice when the TIN is an EIN.

CP 575

The IRS notice issued when an EIN is assigned, showing the exact legal name tied to the number. The name on line 1 of a W-9 should match it.

Notice 972CG

The IRS's proposed penalty notice under IRC 6721 for information returns filed late, incorrectly, or with missing or incorrect TINs. The payer has 45 days to pay, agree in part, or request a waiver for reasonable cause.

IRC 6721 / 6722

Section 6721 penalizes a return filed with the IRS that is late or incorrect; section 6722 penalizes the corresponding statement furnished to the payee. The same per-return amounts apply to each, so one wrong TIN is usually two penalties.

Reasonable cause

The standard under IRC 6724 for waiving an information-return penalty: the failure was due to events beyond the filer's control (for TINs, the payee's failure to give a correct one) and the filer acted in a responsible manner, which for TINs means making the required solicitations.

C-Notice

An IRS notice telling a payer to begin backup withholding on interest and dividends because the payee under-reported that income. Only the IRS can lift it.

SDN list

OFAC's list of Specially Designated Nationals and Blocked Persons. U.S. persons may not pay or otherwise deal with anyone on it, and property must be blocked and reported within 10 business days.

SAM.gov exclusions

The federal government's list of parties excluded from federal contracts, grants and subcontracts, maintained by GSA. Anyone paying with federal funds screens against it.

LEIE

The HHS Office of Inspector General's List of Excluded Individuals/Entities. Federal healthcare programs will not pay for items or services furnished by an excluded party, so healthcare organizations screen vendors and staff against it.

IRIS

The IRS Information Returns Intake System, the free online portal for e-filing 1099-series returns, which the IRS is positioning to replace the older FIRE system.

E-file threshold

Since returns due in 2024, a filer with 10 or more information returns of any type in aggregate must file them electronically.

Payer Master File (PMF)

The IRS database built from every information return and Form 1096 you file, keyed to your EIN. It records what you filed and when, counts of returns with missing or mismatched TINs, extensions and waivers, and your CP2100 and 972CG history. Notice 972CG is generated from it, and the backup withholding compliance check selects cases from it.

List of Payees (LOP)

The enclosure with IRS Letter 6112 in the backup withholding compliance check: every 1099 you filed with a blank payee TIN (or with box 4 withholding), the amount paid, and the backup withholding the IRS computed at 24%. Payee SSNs are shown truncated on the list; your response must use full TINs.

Workstream 1 and 2 (backup withholding)

The IRS's two selection paths in IRM 4.19.26. Workstream 1: information returns filed with no payee TIN and no Form 945. Workstream 2: box 4 withholding reported on information returns and no Form 945. Different defenses apply to each.

IRC 6020(b) return (substitute return)

A return the IRS prepares and files for a taxpayer who did not. In the backup withholding program it follows Letter 6112-A when no signed Form 945 arrives. First Time Abate is not available on a 6020(b) return, which is why signing the IRS-prepared Form 945 is usually better than silence.

Proximal match

In the IRS name/TIN matching routine, a match that tolerates a transposition of the second and third characters of the name control. The Internal Revenue Manual states it applies to SSNs only, so a transposed letter in an individual's surname may pass while the same error on a business name with an EIN fails.

Unpostable (extension or waiver)

An approved Form 8809 extension or Form 8508 waiver that failed to attach to your Payer Master File account because the payer TIN or name control on the form did not match IRS records (codes 501 and 503). Until it posts, it does not protect you from a late-filing penalty.

Tier grace dates

Internal dates in the penalty manual after which a late return is charged at the next tier, set slightly later than the statutory 30-day and August 1 boundaries. A filing that landed a few days past a boundary may still be charged at the lower tier, and a notice that shows otherwise can be disputed.

Letter 6112 / 6112-A

The two letters in the IRS backup withholding compliance check. 6112 encloses the List of Payees and asks for the missing return information; 6112-A encloses a Form 945 the examiner prepared and carries appeal rights. After 6112-A the IRS files a 6020(b) return and assesses.

Compliance check

An IRS contact that asks for missing return information without examining books and records. The backup withholding program is one; the IRS says it is neither an inspection under IRC 7605(b) nor an audit. A payer may decline to participate, but the IRS then proceeds as if there were no response.

Payer Authorization File (PAF)

The IRS's list of payers that have filed the 1099 forms that qualify for the TIN Matching program in one of the last two years. Eligibility is checked against it, so a new payer with no filing history under its EIN can be refused (IRM 5.19.3.5.1.6, 3.42.8.7).

Access Key EIN

In the IRS help desk's search, the EIN that generated a CP2100 or 972CG: the EIN the returns were filed under. If a service bureau or parent filed under its own EIN, the notice went there and a search on the payer's EIN finds nothing (IRM 21.3.11.6.2.6 (superseded by IRM 3.42.7, EPSS Help Desk Support, Sept. 8, 2026 transmittal, effective Oct. 1, 2026; the procedures quoted are from the last 21.3.11 revision)).

Spring Pass

The IRS term for the April CP2100 mailing. Under the assistor script, a Spring Pass notice never requires a correction for the notice's tax year; only the most recent season's return is corrected if the same error carried over (IRM 21.3.11.6.2.4).

Payer Master File (PMF) and PMFOL

The IRS file of Form 1096 and electronic transmittals, one account per payer TIN, which generates Notice 972CG. PMFOL is the command that displays it: a five-year window of counts, penalty columns, warned and penalized years, and backup withholding counts (IRM 2.3.53).

Unpostable codes 501 and 503

The two conditions under which a payer's Form 1096 or electronic transmittal fails to post to the Payer Master File: 501, the payer TIN is not on file; 503, the TIN exists but the name control does not match. Corrected or voided by an examiner without contacting the payer (IRM 3.12.279.112).

Penalty reference number (PRN)

The three-digit code on a 972CG, CP215 or TC 240 civil-penalty assessment that identifies the failure charged. In the information return program 500 is late filing, 501 incorrect media, 502 missing or incorrect TIN, 503 improper format; 500 to 514 are the fifteen combinations of late filing, not e-filing, bad TIN and improper format assessed by the campus from the Payer Master File; 600 series are exam-assessed (IRM 20.1.1.5.3, Exhibit 20.1.1-4).

PENAP (penalty appeal)

Appeals' case type for an assessed penalty, including information return penalties under IRM 20.1.7. Worked mostly by phone or correspondence at Ogden Campus Appeals with a 90-day target, no Tax Court rights, and a rule that the officer will not request documents (IRM 8.11.4).

First Time Abate (FTA)

The administrative waiver of a failure-to-file, failure-to-pay or failure-to-deposit penalty on a clean three-year history. Applies to Form 945 penalties; expressly does not apply to "Form 1099 series information returns" (IRM 20.1.1.3.3.2.1).

ENTLOK (entity lock)

A lock placed on a business's IRS entity after confirmed identity theft, since January 2025, that blocks name, address and responsible-party changes except in writing on Form 8822-B. Older locks (TC 971 AC 524) also block returns and payments from posting to new modules (IRM 25.23.11.6.2.1).

Form 14039-B

The business identity theft affidavit. Often not required: a signed letter with the notice attached starts a case when internal research shows identity theft, and it must not be filed for a return already held by Return Integrity filters (Letter 6042C) (IRM 25.23.11.7.1).

BWI (backup withholding indicator)

The status code on a payee's IRS account under the C-Notice program: 0 no consideration, 1 potentially liable and receiving notices, 2 subject (payers are withholding), 4 satisfied, 8 suspended. There is no equivalent indicator for payers under the B-Notice program (IRM 5.19.3.4).

Mod IEIN prefix

An EIN prefix (20, 26, 27, 33, 39, 45, 46, 47, 81 to 88, 92, 93, 99) that shows the number was issued online. For trusts and partnerships with these prefixes the name control is the first four characters of the name as written, not the surname method used for older EINs (IRM 3.13.2.2).

Sort name

A second, searchable name line on a business's IRS account that holds a trade name, a DBA, or a member's or trustee's name. It is not used in name/TIN matching; only the primary name line produces the name control (IRM 3.13.2.3.7).

Check digit

Two letters the IRS once printed on mailing labels that validate a TIN in place of a name control. Labels stopped in 2009, so almost every paper business return is now keyed by name control instead (IRM 3.24.38.3.4.14.2).

Proximal match (TIN Matching program)

The tolerance the e-Services program applies to SSNs only: the first character of the name control must match, and positions two to four may be transposed or differ by one character (AXCD, ABXD and ABCX all match ABCD). A code 0 for an individual is therefore not proof the full name is right (IRM 3.42.8.7).

96-hour lockout

The TIN Matching program's automatic response when one TIN is queried under different names. Access is blocked for four days; the help desk cannot lift it; a bulk file caught by it returns no result codes (IRM 3.42.8.7.6).

Reporting agent

A company ("not an individual") authorized on Form 8655 to file and sign certain returns electronically, make federal tax deposits, receive duplicate notices and correspondence for the returns and deposits it handled, and provide information to the IRS as an "other third party" (IRM 21.3.9.1.1(1), 21.3.9.2.2(1)). The collection manual calls it "a type of PSP" and says "An employer's use of a reporting agent does not relieve the employer of its employment tax obligations" (IRM 5.1.24.4.3). It may not request penalty abatement, argue facts, appeal, request credit transfers or change the client's address without Form 2848. See reporting agents and Form 945.

Form 8655

Reporting Agent Authorization. Effective from the period shown on the form and "continues indefinitely unless terminated or revoked"; a new Form 8655 does not revoke a prior one, nor a Form 2848 or 8821 (IRM 21.3.9.2.2(3)-(5), Oct. 1, 2026). Line 17 elects duplicate notices; Line 18 extends access to W-2 and 1099-series information "including information about related civil penalties" (IRM 21.3.9.2.2(1)). The signature must be within one year of processing, the revision May 2005 or later, and the name must match Master File on the first four characters (IRM 21.3.9.3.2, 21.3.9.4.2.2). To revoke, re-sign a copy with REVOKE written across the top (IRM 21.3.9.5.2). See Form 8655 letters.

RAF (Reporting Agents File)

The IRS file, maintained by the Ogden Accounts Management RAF team, that records which reporting agent holds authority for which of a taxpayer's forms. Filing indicators cover Forms 940, 941, 943, 944, 945, CT-1 and 1042; EFTPS indicators add Form 720 and one corporate income tax return (IRM 21.3.9.2.5). Forms 941 and 940 may be added without a filing requirement on Master File, but Form 945 and 1042 may not (IRM 21.3.9.3.1(3) Note). Accounts Management checks the RAF before writing to a taxpayer, and authorized agents "will receive duplicates of what is sent to the taxpayer" (IRM 21.3.3.4.16.4(9)-(10), Oct. 1, 2025). A TC 960 posts when an agent is added, TC 961 when removed; "It takes at least two cycles" (IRM 21.3.9.2.4).

Section 3504 agent

A third party appointed on Form 2678 to act as agent for an employer's employment taxes; files an aggregate return under the agent's own EIN with Schedule R and may file Forms 941, 943, 944, 945, CT-1 and CT-2. "Both the section 3504 agent and the employer are liable for the employer's employment taxes while the agent authorization is in effect" (IRM 5.1.24.4.4); a TC 971 with action code 382 through 385 on the employer's entity cross-references the agent's EIN (IRM 5.1.24.4.4.1). Unlike a payroll service provider or reporting agent, which the manual says have no liability, the 3504 agent shares it.

CPEO (certified professional employer organization)

A professional employer organization certified by the IRS. It is "treated as the only employer" for the worksite employees it pays, concurrently liable with the customer for non-worksite employees, files aggregate Forms 940, 941 and 943 with Schedule R under its own EIN, reports its contracts on Form 8973, and must notify customers within 10 days if its certification is suspended or revoked (IRM 5.1.24.6.1). A non-certified PEO is different: for quarters after March 31, 2014 "the payor and employer are concurrently liable," and state PEO licensing "has no bearing" on federal liability (IRM 5.1.24.6.2, 5.1.24.6(3)).

Payer Agent file

The IRS underreporter program's list of payers whose information returns "have been verified as erroneously filed or processed or determined potentially fraudulent," kept by tax year and keyed by EIN, document type and filing source (IRM 4.19.3.6(1)). A campus coordinator begins research "when four or more cases with the same EIN are identified"; once a payer is listed with delete or accept instructions, payee cases built only on its returns close without a notice (process code 24). Payers can report their own systemic filing errors through the ECC-MTB Information Returns Division. See why a correct 1099 still triggers a CP2000.

Form 2624

Consent for Third-Party Contact. In an individual underreporter case the IRS will not write to a payer about a disputed 1099 until the payee signs one naming that payer, one form per payer (IRM 4.19.3.23.9.6(1)). A copy is enclosed with the resulting Letter 2625-C. See Letter 2625-C.

Non-select table

Exhibit 4.19.3-10 of the underreporter manual: words in a payee or payer name line (ESTATE, TRUSTEE, TTEE, CUSTODIAN, FBO, AGENT, INC, CORP, ITF, UGMA and others) that cause an information return to be left out of matching against an individual's Form 1040 when the payee is not the taxpayer. The way a payer formats a fiduciary or custodial recipient name decides whether the return is matched at all.

CAWR (Combined Annual Wage Reporting)

The IRS program that reconciles the wages and withholding an employer reported on Forms 941, 943, 944, 945 and Schedule H (the "94X" returns) to the W-2s SSA processed and the 1099-Rs and W-2Gs the IRS holds. "IRS matches four fields, Social Security wages, Social Security tips, Medicare wages and tips, and Federal Income Tax (FIT) withheld," and a case opens on "an apparent underpayment of taxes or over withholding of FIT" (IRM 4.19.4.1.8(2)). Cases are worked two to three years after the W-2s were due in the CATRS system; the CAWR module on a transcript is MFT 88, and blocking series 55 on the last quarter marks a CAWR tax adjustment (IRM 4.19.4.11.1). Backup withholding on Forms 1099-NEC, MISC, INT and DIV is not part of the match. See the CAWR guide.

SSA-CAWR vs IRS-CAWR

The two components of CAWR. IRS-CAWR is the tax side: it compares the 94X returns to W-2s, 1099-Rs and W-2Gs and issues Letter 99-C, the "Letter of Employment Tax Problem"; unanswered cases are assessed as employment tax on the last quarter of the year (IRM 4.19.4.1.1(2), 4.19.4.3.48(4), 4.19.4.4). SSA-CAWR is the penalty side: after SSA has written twice about W-2s it could not reconcile, the IRS issues Letter 98-C proposing information return penalties under IRC 6721; no reply by the 11-cycle suspense posts status 91 and assesses the intentional disregard penalty automatically (IRM 4.19.22.2(1); IRM 4.19.4.3.1(5)). Withholding mismatches are always IRS-CAWR, because "SSA only matches three fields during their reconciliation" (IRM 4.19.4.1.8(9)).

PRN 549

Penalty reference number for the CAWR intentional disregard penalty under IRC 6721(e), "Imposed on employers who do not comply with our requests to file correct Forms W-2." The manual uses "only the 10 percent of the aggregate amount method," applied to the larger of the Social Security (wages plus tips) or Medicare wage discrepancy between the 94X returns and the W-2s, and "There is no maximum to the Intentional Disregard penalty" (IRM 4.19.4.3.1.1(1) and (2), June 11, 2025). Assessed automatically at status 91 and on a payment sent without explanation; excluded from First Time Abate by Chief Counsel (IRM 4.19.4.3.1(1) Note, 4.19.4.3(9)). Billed on CP 215 on the civil penalty module, MFT 13. See the CAWR penalty estimator.

PRN 550

Penalty reference number for the CAWR late-filing penalty under IRC 6721(a), assessed "in the reply phase, when original Forms W-2 filed in response to SSA-CAWR correspondence are received." The forms "are always subject to the maximum penalty of $290.00 ($280 for tax years 2020-2021, $270 for tax years 2018-2019, $100 for tax years 2010 through 2014 and $50.00 for SSA CAWR tax years 2009 and prior) for each Form W-2" (IRM 4.19.4.3.1.2(1)), and only when there are "two or more Form W-2" (IRM 4.19.4.3.1.3(3)). W-2s postmarked within 10 days of the CP 215 date convert PRN 549 on those forms to PRN 550 (IRM 4.19.4.6.1(8)). Not eligible for First Time Abate. See the CAWR penalty estimator.

Action 61 / Policy Statement P-21-3

The IRS's reply-time standard for taxpayer correspondence. It came out of a review of "Corporate Critical Success Factor 61" and was written into Policy Statement P-21-3, formerly P-6-12 (IRM 21.3.3.1.8). The core rule: "Final response to taxpayer(s) must be initiated by the 30th day from the earliest IRS received date, unless the taxpayer has received an interim contact or interim contact has been initiated from the IRS by the 30th day" (IRM 21.3.3.1.9). Cases must be controlled within 14 days and age at 45 (IRM 21.3.3.4(1); 21.3.3.4.1(6)). Where a Code provision conflicts, "IRC governs." Amended returns, Form 94XX, extensions, address changes and payment-only letters are excluded from the standard (IRM 21.3.3.2(3)). See what happens to your letter at the IRS.

Interim letter

A letter the IRS sends when it cannot give a final answer within 30 days of the received date; it satisfies the P-21-3 clock without deciding anything. "An interim letter is required to be sent within 30 days of the received date if a final response cannot be issued," and each one must state when the final response will be mailed (IRM 21.3.3.4.2.2(1)-(2), June 2, 2023). Letter 2645C is the usual first interim, Letter 2644C the second, which "must include the specific reason for the delay" (IRM 21.3.3.4.2.2(4)); Letter 86C is the interim used when the case is transferred to another office, promising "an additional 60 days" (IRM 21.3.3.4.2.1). Since January 2018, interim letters generated by Accounts Management systemically promise 60 days (IRM 21.3.3.4.2.1(3)). See the notice decoder and what happens to your letter at the IRS.

Correspondence date

The date the IRS quotes back as the date of your letter ("your letter dated ...") and enters with an adjustment so the resulting notice reads "This is the result of your inquiry of (fill in)" (IRM 21.3.3.4.2.3(6)). The manual picks it in order: the date the correspondence "was prepared or signed"; the "Transmission date on a fax or electronic submission receipt"; the envelope postmark; the SCAMPS digital date stamp; "Three calendar days prior to the IRS received date of the case"; the current date (IRM 21.3.3.4.2.3(5)). "Don't use the IRS received date as the correspondence date unless otherwise noted" (IRM 21.3.3.3.4(3)). On a business account with no monetary adjustment, entering it is not required (IRM 21.3.3.4.2.3(4) row 5). Date and sign every letter. See what happens to your letter at the IRS.

Form 4442 (e-4442)

Inquiry Referral: the internal form an IRS assistor prepares when a phone, chat or walk-in inquiry cannot be resolved during the contact. The assistor is told to "Offer to prepare a referral and advise the taxpayer of the 30 day timeframe" (IRM 21.3.5.2(1)); the promise is contact or resolution within 30 calendar days (IRM 21.3.5.4(1)). "A fax from a taxpayer or any written correspondence" is not a referral (IRM 21.3.5.2.1). Duplicates within 7 calendar days are blocked, and after the 30 days lapse without Taxpayer Advocate criteria the assistor may "NOT generate another Form 4442/e4442" (IRM 21.3.5.4.2.1.1(1); 21.3.5.4.2.1.1.1(2)). Once written, the referral "becomes correspondence for the purpose of Policy Statement P-21-3" (IRM 21.3.3.2(3)). See calling the IRS about a 1099 notice and what happens to your letter at the IRS.

Form 1042-T

Annual Summary and Transmittal of Forms 1042-S, the cover sheet that must accompany paper Forms 1042-S Copy A. One 1042-T is filed per type of 1042-S, and it must match the attached forms on five checkboxes: Line 1a to Box 3, Line 1b (Amended) to the Amended box, Line 1c to Box 15, Line 1e to Box 7c and Line 1f to Box 7d (IRM 3.21.111.7(1)-(3), Jan. 1, 2024; 3.21.111.7.1(2), Sept. 8, 2025). It posts to the Payor Master File, MFT 88 (IRM 3.21.111.1.1(4)). A 1042-T filed without Copy A "will be destroyed, per local procedures" and no correspondence is generated (IRM 3.21.111.7(14)); Copy A filed without a 1042-T gets a dummy transmittal built by the IRS (IRM 3.21.111.8(3)). See what happens to a paper Form 1042-S inside the IRS.

Code and Edit

The IRS Submission Processing function (also called Document Perfection) that reads a paper return before it is transcribed, corrects or "perfects" fields the computer could not read, and edits action codes for the next stage. For paper Forms 1042-T and 1042-S the work is done at the Ogden campus under IRM 3.21.111. The manual says the function "is not responsible for the mathematical verification of the return or for checking the validity of the documents being processed" (IRM 3.21.111.1(3)); validity, math and consistency checks happen later in the Chapter Three and Chapter Four Withholding database (IRM 3.21.111.1(4)). Editors "Take taxpayer intent into consideration" and refer anything not covered to a lead (IRM 3.21.111.2). See what happens to a paper Form 1042-S inside the IRS and what happens to a paper 1099 inside the IRS.

Dummying

Code and Edit's term for re-keying a filer's submission onto a blank official current-year form so it can be transcribed. Paper Forms 1042-S "filed on a form, or in a format, that does not exactly match the official IRS form" are dummied; a consolidated listing or a form with several income codes on one page is split so the examiner can "dummy a Form 1042-S for each Recipient," and two forms on one sheet are photocopied so each gets its own DLN (IRM 3.21.111.6(8)-(10), Jan. 10, 2024). A prior-year form revision that cannot be edited to current-year line numbering is dummied (IRM 3.21.111.8(6)), and Copy A received without a Form 1042-T gets a dummy 1042-T (IRM 3.21.111.8(3)). See what happens to a paper Form 1042-S inside the IRS.

Chapter 3 status code

The two-digit code in Form 1042-S box 13j (recipient; box 13f before 2026) and Box 12b (withholding agent) identifying the party's status for chapter 3 withholding purposes, for example 15 for a corporation, 16 for an individual and 21 for an unknown recipient, which must carry "Unknown" as Name Line 1 (Exhibit 3.21.111-3 Note). The Sept. 8, 2025 revision of the Code and Edit manual added codes 39 (Disclosing QI), 40 (Partnership QDD) and 41 (U.S. government or tax-exempt entity other than 501(c)) (Exhibit 3.21.111-3). A missing recipient code gets "limited research" from the name line or an attached explanation; otherwise processing continues (IRM 3.21.111.8.1.36). Chapter 4 status codes are a separate list, 01 to 50, in Exhibit 3.21.111-4. See what happens to a paper Form 1042-S inside the IRS.

Form 8300

Report of Cash Payments Over $10,000 Received in a Trade or Business. An information return under IRC 6724(d) that any person in a trade or business must file within 15 days of receiving more than $10,000 in cash in one transaction or related transactions (IRM 4.26.10.3(1)). One filing is "dual purpose," satisfying IRC 6050I and 31 USC 5331 (IRM 4.26.10.1.2). A written statement to each customer named on the form is due by January 31 of the following year (IRM 4.26.10.7.2). Penalties are the IRC 6721 and 6722 amounts, with no August 1 tier and no de minimis exception (IRM 4.26.10.10.1(8)). See Form 8300 for businesses that take cash.

Related transactions (Form 8300)

Transactions that are aggregated toward the $10,000 threshold: any between the same payer (or agent) and recipient within 24 hours, plus transactions over a longer period if the recipient "knows, or has reason to know" they are a connected series (IRM 4.26.10.5.5(2)). Installments are aggregated within a year until they exceed $10,000, reported within 15 days of the tipping payment, and then a new Form 8300 is due each time previously unreported payments in a 12-month window exceed $10,000 (IRM 4.26.12.12.1(3)-(5), Aug. 21, 2019). A construction transaction is the whole contract "including all change orders and add-ons" (IRM 4.26.12.4.6(1)).

Cash equivalent (Form 8300)

A cashier's check, bank draft, traveler's check or money order with a face amount of $10,000 or less. It is treated as cash for Form 8300 when received in a designated reporting transaction (a retail sale of a consumer durable priced over $10,000, a collectible, or travel or entertainment over $10,000) or in any transaction where the recipient knows it is being used to avoid reporting; a personal check is never cash (IRM 4.26.10.5.3, 4.26.10.5.4). Sales tax and fees count toward the amount reported but not toward the consumer-durable price test (IRM 4.26.12.10.1(4)-(5), Aug. 21, 2019), and cash equivalents paid for services are not reportable "because services are not a designated reporting transaction" (IRM 4.26.12.10.1(1)).

Title 31 vs Title 26 (Form 8300)

The two bodies of law one Form 8300 serves. Title 26 (IRC 6050I) is administered by the IRS: IRC 6721 and 6722 penalties, reasonable-cause relief, a three-year statute on filed forms and none on unfiled forms or the customer statement (IRM 4.26.10.11.1). Title 31 (31 USC 5331) is FinCEN's: the IRS examines but cannot assess, negligence and willful penalties have "no limitations or reductions" and "no waiver for reasonable cause," and the statute is six years from the transaction (IRM 4.26.10.10.4, 4.26.10.11.2). The customer statement is a Title 26 requirement only, so a Title 31 exam does not check it (IRM 4.26.11.8.3.2(11)). Letter 1112 closes a Title 31 violation case; Letters 4595 and 4596 close Title 26 penalty cases (IRM 4.26.11.7.1.1).

Claim for refund vs request for abatement

A claim for refund asks for refund or credit "of amounts already assessed and paid"; a request for abatement is one where "the IRS assessed the tax but the taxpayer has not paid. It is not a claim for refund" (IRM 4.23.13.1.6). The same Form 843 is one or the other depending on "whether the amended return or written request asked for a refund at the time it was filed," and "A request for abatement cannot be retroactively converted to a claim for refund" (IRM 4.10.11.2.1.2(4)-(5), Sept. 4, 2020). A claim carries Appeals and suit rights; a denied abatement request has "no appeal rights beyond the group level without paying the tax and filing a claim for refund" (IRM 4.23.13.4.1.4(2)). See Form 843: claim or abatement.

RSED (refund statute expiration date)

The last day to file a claim for refund: three years from the filing of the return or two years from the payment, whichever is later (IRM 4.23.13.2.2). For a penalty the payment usually governs, and "taxpayers will always have at least 2 years from the date of any payment to request a refund of such payment" (IRM 4.10.11.5.2.3(6) note, Sept. 29, 2022). A Form 945 filed before April 15 is "deemed filed" on April 15, so its three-year RSED runs from April 15 (IRM 4.23.13.2.2). An abatement request has no RSED (IRM 4.23.13.2.2(4)). The RSED field on an IRS transcript "is not necessarily indicative of the last date to file a claim" (IRM 4.10.11.5.2(2) caution).

Form 2297

Waiver of Statutory Notification of Claim Disallowance. Signing it waives the certified Letter 905 or 906 and "starts the two-year period for the taxpayer to file suit as allowed in IRC 6532" (IRM 4.23.13.3.4). It "does not constitute a 'decision of the IRS'" that lifts the six-month no-suit bar (IRM 4.10.11.2.2.1(3)) and is never used on abatement requests or audit reconsiderations. Compare Form 3363, the agreed acceptance of a disallowance, which "does not waive the taxpayer's right to file suit" (IRM 4.23.13.3.5).

IRC 6532 (period for refund suit)

The window for suing on a disallowed claim for refund: "no earlier than six months after the filing of the refund claim (if no action is taken by the IRS), and no later than two years" from the certified notice of disallowance or a signed Form 2297 (IRM 4.10.11.2.16.2(1); IRM 4.23.13.3.4). The two years "is not suspended during any period in which the IRS considers or reconsiders the claim" or during Appeals (IRM 4.10.11.2.16(4)); Form 907 can extend it if signed before it expires (IRM 4.23.13.8). Letter 917 and Letter 5376 do not start it. See Form 843: claim or abatement.

Q- freeze

An IRS account freeze set "when the module contains more credits than claimed on the return"; the credit "is frozen from refunding or offsetting for 15 cycles from the posting of the TC 150" (IRM 3.14.2.6.8(1)). It produces CP 267 (no math error) or CP 268 (math error). Released when the module reaches zero or a debit, when a credit reversal brings posted credits back within a redacted tolerance of the amount claimed, when an employee inputs a TC 290 for $.00 with priority code 4, or when the 15 cycles run out (IRM 21.7.11.4.9(2)). On Form 945 the usual cause is backup-withholding deposits that exceed the tax on the return. See CP 267 / CP 268.

-A freeze

The account freeze set when a second return (TC 976) posts to a year that already holds a return (TC 150). It "prevents any refund or offset from the module until an adjustment (TC 29X) is made" (IRM 21.7.9.2(1)). Also set by TC 971 AC 010 when an amended or X return bypasses processing. Duplicate filing conditions "age in 45 days and are not considered correspondence" (IRM 21.7.9.2(4)). See a second Form 945 for the same year.

TC 976

Transaction code for a second return posting to a tax module that already contains an original return (TC 150). Which return is the TC 150 depends on processing order, not filing order or the payer's intent. A TC 976 with computer condition code G is a return marked amended, corrected, supplemental or superseding, and "IDRS does not record any information on 'G' coded returns, except the amount paid with the return" (IRM 21.7.9.3(2)). A TC 976 with CCC G and filing location code 93 is a Form 945-X filed through MeF (IRM 21.7.9.4.1.2.2).

Superseding return

"A superseding return is a second (or subsequent) return filed on or before the filing due date, including extensions. The second return replaces the original return. Whether a return is superseding depends on the order in which the returns were filed, not the order in which they were processed" (IRM 21.7.9.3.3). For Form 945 it forces a fresh deposit-penalty computation and referral to Examination for classification (IRM 21.7.9.3.3.1). The IRS does not date-stamp or keep envelopes for timely returns, so the payer's proof of filing is the evidence. See a second Form 945 for the same year.

Form 9409 (IRS/SSA Wage Worksheet)

The form the IRS identity theft unit sends to the Social Security Administration to remove wages from a taxpayer's earnings record when "a social security number is used by someone other than the SSN owner for employment purposes" (IRM 25.23.13.3.1(1)). It is prepared only for wage income containing Social Security wages, transmitted on Form 3210, resubmitted if SSA has not acknowledged it within 60 days, and never submitted more than twice. It is not prepared when the employer has already filed a Form W-2c, when the SSN was TIN perfected ("These will be rejected by SSA"), when IRPTR shows the wages as INVALID, or when the taxpayer holds an SSA determination letter (IRM 25.23.13.3.1(4)). It is the only mechanism in the income-related identity theft manual that changes a record outside the IRS, and it goes to SSA, not to the employer. See when a payee says your 1099 or W-2 isn't theirs.

TC 971 AC 501

The transaction code and action code the IRS posts to a taxpayer's account to record a tax-related identity theft determination. In an income-related case, where someone used the taxpayer's SSN on a W-2 or 1099 and an assessment or refund issue resulted, the closing marker is TC 971 AC 501 with the literal INCOME, with Letter 4674C "if applicable" (IRM 25.23.13.3(7)). Its siblings are TC 971 AC 504 (non-tax-related, taxpayer-identified; field EMPL-M, which requires a manual Letter 4402C) and TC 971 AC 506 (IRS-identified, closing Letter 4674C) (IRM 25.23.13.3(8)-(9)); additional years found later carry the literal ICMCCA (IRM 25.23.13.3(10)). The marker sits on the payee's account; the payer's information return is not changed or removed.

UD indicator

The undeliverable indicator, TC 971 AC 661, that the entity unpostable unit posts to a business account when correspondence comes back and no better address can be found, along with TC 593 on the open filing requirements (IRM 3.13.222.112). The indicator blocks the IAT Letter Tool until the address is corrected (IRM 3.13.222.2(9)), so an account carrying it receives no entity letters, including Letter 147C. The unit will not take a new address from a letterhead or a return-address envelope; it accepts Form 8822-B, a signed statement with the full name and EIN, or a USPS forwarding sticker. See the business name change checklist.

IRPTR

The IDRS command code IRS employees use to view or order transcripts of information returns from the Information Returns Master File, for "a particular Payee (online or Hardcopy) or Payer (Hardcopy only)" (IRM 2.3.35.1(1)-(2), Mar. 5, 2025). Definer O shows one payee document, L the payee summary with money totals and best addresses, I an online payer summary, R a hardcopy payer transcript, J the nonfiler summary and W a sanitized taxpayer copy. Ten tax years are online; the oldest is purged at noon Eastern on January 1 (IRM 2.3.35.2, 2.3.35.4). See what the IRS sees when it pulls up your 1099.

IRMF (Information Returns Master File)

The IRS database that holds every 1099, W-2, 1042-S, K-1 and other information return that passed final format checks, read by command code IRPTR. The manual calls it "a steady state legacy system" (IRM 2.3.35.1(1), 2.3.35.1.6). Each document carries an ON FILE DATE, the "Date this document passed final valid format checks and became part of the IRMF"; the file is refreshed weekly, and new-year 1099 data is not online until late January (IRM 2.3.35.2, 2.3.35.10.1(2)). Corrected and original returns are stored side by side with separate money totals (IRM 2.3.35.10.6(2)). Distinct from the Payer Master File (PMF), which holds payer-level counts, and from the Information Returns Database (IRDB) that holds ACA Forms 1094 and 1095.

TIN description

An IRS-generated field on every information return in the IRPTR payee document screen recording the IRS's verdict on the payee TIN as filed. Exactly eight values exist: "INVALID / IRS VALID PERFECTED SSN / INVALID PERFECTED SSN / VALID PERFECTED SSN / VALID PERFECTED EIN / IRS VALID SSN / VALID SSN / VALID EIN" (IRM 2.3.35 Exhibit 2.3.35-63 line 4.3, Jan. 20, 2026 transmittal). The manual does not define "IRS VALID" as against "VALID." On the payer screens the same verdict shows in punctuation: an SSN the IRS considers invalid displays as nine unhyphenated digits (Figure 2.3.35-5). Four of the eight values say the IRS had to repair the TIN; see the IRPTR guide and IRS TIN Matching.

TIN perfection

The IRS's repair of a payee TIN on an information return that did not validate as filed. Four of the eight TIN DESCRIPTION values on the IRPTR screen record it: VALID PERFECTED SSN, IRS VALID PERFECTED SSN, INVALID PERFECTED SSN and VALID PERFECTED EIN (IRM 2.3.35 Exhibit 2.3.35-63 line 4.3, Jan. 20, 2026 transmittal); the manual does not say how the perfection is done. The underreporter manual treats a TIN-perfected return differently when a payee disputes it (IRM 4.19.3.23.9.1(6)). A perfected TIN is not a TIN that matched as filed. See what the IRS sees when it pulls up your 1099.

ATIN (Adoption Taxpayer Identification Number)

A temporary nine-digit number for a child in a pending domestic adoption whose SSN is not yet available. It begins with 9 and its fourth and fifth digits are 93, a group the ITIN manual says is "reserved for other programs" and "NOT used" for ITINs (IRM 3.21.263.2(10); 3.21.263.9.3.5(4)). A 9xx number with 93 in the middle offered on a W-9 is not the payee's ITIN. See the TIN format checker.

IRSN (Internal Revenue Service Number)

A temporary internal placeholder the IRS assigns to a taxpayer account that has no SSN or ITIN, for example a FIRPTA Form 8288 that arrives with a remittance and no TIN (IRM 3.21.263.6.9.1). It begins with 9 and its fourth and fifth digits are a campus code: 01 to 10, 17 to 19, 28, 29, 37 to 39, 49, 66 or 89 (IRM 3.21.263.5.5; 3.21.263.9.3.5(4)). "An IRSN is not a valid TIN" and "is used only as an internal identifying number or until the taxpayer is assigned an SSN or ITIN" (IRM 3.21.263.6.4.1 Reminder; 3.21.263.5.5(3)). It will not TIN-match and should not be accepted on a W-9. See which 9xx numbers are ITINs.

DM-1

The IRS validation file of TINs paired with name controls and dates of birth, drawn from SSA and ITIN records, against which names and TINs on returns are checked. The ITIN manual treats an ITIN as "invalid" on a return when "the ITIN and name on DM-1 do not match" (IRM 3.21.263.2.1(2) Note). Expired ITINs remain on DM-1 with their name control; revoked ITINs "are removed from DM-1. DM-1 will not contain any data for the ITIN such as name control or DOB" (IRM 3.21.263.2.1(6) Note). ITIN-to-SSN account merges may sit on the invalid side of the master file until "the quarterly DM-1 update" (IRM 3.21.263.6.7(2) Exception), which is why a payee's new SSN can fail a name match for a quarter. See IRS TIN matching.

CP 565

The ITIN assignment notice, the "Assigned, Active / Inactive, or Renewed Notice" that "Includes an Active or Inactive indicator" (IRM 3.21.263.5.9). CP 565 A is the systemic notice; CP 565 B is a reissued copy. It regenerates on any name or address change, and "These notices are not necessarily indications the ITIN is renewed" (IRM 3.21.263.2.3(2) Reminder), so a payer accepting one with a W-9 should read the indicator, match the W-9 name to the notice name, and still run TIN matching. If a Certifying Acceptance Agent that is a financial institution filed the W-7, "the notice will only be issued to the CAA" (IRM 3.21.263.5.9(3)). See the CP 565 acceptance checklist.

Assessable penalty

A civil penalty "not covered by deficiency procedures of IRC 6211 through IRC 6215" and "paid upon notice and demand. For assessable penalties, there is no 30-day letter, no agreement form, and no notice requirements prior to assessment" (IRM 20.1.9.1.5(2)). Information-return and most miscellaneous penalties are assessable: they are proposed (if at all) on Form 8278, posted to MFT 13 for a business, and billed on CP 215. Appeals offers "a prepayment, post assessment appeal process" for them (IRM 20.1.9.1.5(5)). See Penalties reasonable cause cannot remove.

Form 8278

Assessment and Abatement of Miscellaneous Civil Penalties, the internal IRS form on which an examiner asserts an assessable penalty. One is prepared "for each type of penalty, for each tax year, and for each IRC section," with a Form 886-A stating the basis, "Why reasonable cause or other penalty relief does not apply," the computation and the taxpayer's position (IRM 20.1.9.2.2(2)-(3), Jan. 29, 2021). "The taxpayer's signature is not required." "Both the originator and supervisor sign and date each page of the form on which penalties are proposed," or the file is returned on Form 3210 (IRM 20.1.10.2(9)). The penalty then posts to MFT 13 and generates CP 215.

IRC 6705 (broker notice of backup withholding)

The penalty on a broker that acquires a readily tradable instrument for a customer and fails to "notify the payor of such instrument within 15 days of the acquisition that the payee is subject to backup withholding" (IRM 20.1.10.13(2)). The notice must carry the payee's name, address and TIN, the IRC 3406(a)(1) condition, and where applicable a statement that the IRS notified the broker; "Upon receiving the notice from a broker, the payor must impose withholding on the account" (IRM 20.1.10.13(3)-(4)). $500 per willful failure, PRN 632. "Penalty relief is not granted for reasonable cause"; pay in full, then file a claim for refund (IRM 20.1.10.13.3). See the notice template.

IRC 6682 (false W-4 or W-9 statement)

A civil penalty on "any individual who makes a statement under IRC 3402 ... or IRC 3406, Backup Withholding, that results in a decrease in the amounts deducted and withheld ... if it had no reasonable basis at the time the statement was made" (IRM 20.1.10.10(1)). $500 per false statement, PRN 616, assessed on Form 8278 against the payee, not the payer. Relief if there was "reasonable basis for the statement at the time"; waived "if the individual's taxes for that year are equal to or less than the sum of the: Allowable credits ... and Estimated tax payments" (IRM 20.1.10.10.2(2), 20.1.10.10.3). It is the penalty behind the jurat on Form W-9.

IRC 6657 (dishonored payment, including EFTPS)

The bad-check penalty, extended since July 2, 2010 to "any 'instrument in payment, by any commercially acceptable means,'" including "EFTPS payments and deposits" (IRM 20.1.10.7(2)). 2% of the payment if $1,250 or more; $25 if $25 to $1,249.99; the payment amount if $5 to $24.99 (IRM 20.1.10.7.1(1)). Posts as TC 280 or TC 286. Relief only in writing: "Oral testimony to that effect will not be accepted. The first time abate (FTA) administrative waiver does not apply," and "A bank letter is required if the reason is bank error" (IRM 20.1.10.7.3); reason codes PRC 017 (bank error), 032 (EFTPS or Treasury Financial Agent), 045 (stop payment) and 044 (IRS advice) (IRM 20.1.10.7.4). See the IRC 6657 calculator.

TIN compliance glossary