| Notice | Sent to | Deadline |
|---|---|---|
| CP2100 / CP2100ANotice of possibly incorrect or missing payee TINs | Payer | Mail B-Notices within 15 business days of the notice date or receipt (later of the two); begin 24% backup… |
| Notice 972CGNotice of proposed civil penalty for information returns | Payer | 45 days from the notice date (60 if you're outside the U.S.) to agree, agree in part, or request a waiver… |
| CP15Notice of penalty charge (civil penalty assessed) | Payer | Pay by the date shown, or request abatement / file an appeal, generally within 30 days of the notice date to… |
| CP504 / CP504BFinal notice, intent to levy | Payer | Pay, set up a payment plan, or resolve the underlying penalty before the date shown. |
| Letter 686-BExtension granted in the backup withholding compliance check | Payer | The new date on the letter. |
| Letters 6509C, 6510C, 6526CTCC application status letters | Transmitter | Act before the 90-day deletion or the dormancy drop; the letter states the date. |
| C-Notice: CP543 and CP544 (backup withholding notification)IRS instruction to start, or stop, withholding on a payee who under-reported | Payer (interest, dividends, patronage dividends, OID) | Begin 24% withholding within 30 business days of the CP543 on all reportable interest, dividend, patronage… |
| Letter 2027-C (and Letter 1979-C)Payor stop letter: quick release from C-Notice withholding | Payer | Stop within 30 days of the letter date. |
| CP546Special backup withholding listing for a successor payer | Successor payer | None; it is a request you make. |
| Letter 3667-CGeneric reply when a CP2100 is sent back to the IRS | Payer | None. |
| Letter 252CBusiness name on a return needs verification | Payer or payee business | Per the letter. |
| CP 201, CP 209 (EIN consolidation)Two EINs for one entity: mismatch, or merged | Payee business | Per the notice. |
| CP539 (to the payee)IRS notification to a taxpayer that they are subject to backup withholding | Payee | The payee has the response window on the notice to dispute it with the IRS. |
| Letter 147CEIN verification letter | Payee (business) | No deadline of its own; the payee needs it within the payer's 30-business-day B-Notice window. |
| CP 575EIN assignment notice | Payee (business) | None. |
| CP136 / Form 945 deposit noticesDeposit-frequency and Form 945 correspondence | Payer | Per the notice; a missing-945 notice typically gives 30 days. |
| Letter 1948-CIRS needs more information on your 972CG response | Payer | 30 days (60 outside the U.S.). |
| Letter 854-CPenalty waiver denied, with appeal rights | Payer | Appeal to the Independent Office of Appeals; the letter states the window. |
| Letter 6304-CCase closed: waiver granted, or request incomplete | Payer | None if the waiver was granted. |
| Letter 6112Backup withholding compliance check: 1099s with no TIN and no Form 945 | Payer | 30 days on the letter; the IRS's internal cut-off is 45. |
| Letter 6112-AProposed Form 945 prepared by the IRS | Payer | 30 days. |
| Letter 3064-CYour backup withholding response was incomplete | Payer | The original 6112 or 6112-A date still applies. |
| Notice 972FTIN corrections for federal and quasi-governmental agencies | Federal agency payer | None stated; correct the TINs and solicit as usual. |
| Letters 5381, 5382, 5383, 5365Extension or e-file waiver decisions | Payer | A denied 8508 can be reconsidered within 30 days of the letter (60 outside the U.S.). |
| Letter 1865-CUnprocessable paper information returns | Payer | 45 calendar days before the case goes to the penalty unit; respond by the date on the letter if earlier. |
| CP2000Proposed changes to a payee's return from unreported income | Payee (caused by a payer) | The payee has about 30 days from the notice date to respond; the payer's correction will not post in time… |
| CP 207 / CP 207LForm 945-A (record of tax liability) missing, negative or not equal to the tax | Payer | 45 days to supply a corrected Form 945-A; assessment at week 15. |
| CP 276A / CP 276BDeposit penalty computed but waived (educational notice) | Payer | No response required. |
| CP 238First-time depositor: deposit was late or misdirected, penalty waived | Payer | No response required. |
| CP 568Failure-to-deposit penalty computation | Payer | Follows the penalty notice; no separate deadline, but the 90-day 6656(e) window runs from the 23C date of… |
| Letter 313-CProposed failure-to-deposit penalty: liability schedule needed | Payer | 45 days to return a valid schedule; 20 days after a warning. |
| Letter 2782-CIRC 6656(e)IRC 6656Internal Revenue Code, Cornell LII deposit designation request received too late | Payer | None; the request is closed. |
| Letter 5263CEntity fabrication: the IRS suspects the EIN itself is fraudulent | Business / individual | As stated in the letter; the entity may be locked (TC 020) until resolved. |
| Letter 6217CYour business entity has been locked (ENTLOK) | Business | None. |
| Letter 916CClaim or amended return not processed (no consideration) | Business | None stated; in the penalty context, the appeal rights in the earlier denial (Letter 854-C) govern. |
| Letter 544Apology: federal tax lien filed in error | Business | None. |
| CP 236Reminder to a new semiweekly depositor that no deposit was received | Payer | Informational; the deposits it refers to are already due. |
| Letters 1277 / 1278Appeals decision on a penalty appeal (PENAP) | Payer | Administrative end of the line. |
| Letters 5316C / 5317CBusiness identity theft: acknowledgment and request or closing letter | Payer | 30 days to respond to a 5317C request; the case is suspended 45 days (60 for a foreign address). |
| Letter 6042CEntity verification: a business return under your EIN is held in Return Integrity filters | Payer | 30 days from the letter date to reply, by fax to 844-201-5531 or as the letter directs. |
| Letter 4552CBusiness underreporter: verification request to the payer who filed the 1099 | Payer | 60 days monitored for a reply. |
| Letter 4838Payroll Service Provider Client: initial contact when your provider failed to deposit or file | Payer | No fixed response period is stated in the manual; respond by the date on the letter. |
| Form 8655 lettersReporting agent authorization returned, rejected or not added to the RAF | Payer | Paper listings are returned within 30 days, electronic ADD listings within 10 business days (IRM 21.3.9.3.6IRM 21.3.9.3.6Internal Revenue Manual, irs.gov… |
| Letter 2625-CPayer verification request in a payee's underreporter case | Payer | No deadline printed in the manual; the payee is told the IRS will recontact them within 60 days, and a… |
| Letter 2626-CUnderreporter correspondence to the payee: more information, extension, or the payer's answer | Payee | 30 days in the ordinary case; "Do not issue multiple Letter 2626-Cs to request the same information" (IRM… |
| CP 2501Underreporter inquiry: the IRS asks before it proposes | Payee | A phone request earns a 15-day extension; if no response is received "within 45 days of the notice date, a… |
| CP2000 series A to E (payee side)Proposed changes to a payee's return built from payer information returns | Payee | Due 30 days from the notice date; one 30-day extension by phone; a written request gets Letter 2626-C and… |
| CP 3219AStatutory notice of deficiency after an unresolved CP 2000 | Payee | 90 days (150 outside the U.S.) to petition; no extension. |
| Letter 98-CSSA-CAWR: W-2s SSA could not reconcile to your Forms 94X; penalty proposed | Payer | 45 days. |
| Letter 99-CIRS-CAWR "Letter of Employment Tax Problem": your 94X totals do not match the W-2s, 1099-Rs or W-2Gs | Payer | The manual states no reply window for Letter 99-C; the 45 days on Letter 98-C is the working assumption. |
| Letter 2057-CCAWR closing or explanation letter; may ask for more reasonable-cause detail | Payer | Reply by the date on the letter; a case awaiting more information is suspended and then assessed. |
| Letter 2645CInterim response: the IRS has your letter but has not finished with it | Payer | No action required. |
| Letter 2644CSecond interim response: the promised date was missed, with a stated reason | Payer | No action required. |
| Letter 86CYour correspondence was transferred to another IRS office | Payer | No action required. |
| Letter 135CPower of attorney needed: the IRS will not answer the person who wrote | Business | No deadline. |
| Letter 104CAddress change not made: the request was unsigned | Business | No deadline, but the old address remains the address of record and notices keep going there. |
| Letter 2277Form 8300 appointment letter: a Bank Secrecy Act examination is opening | Business | Appointment date in the letter; a minimum of 10 business days to secure a representative (IRM 4.26.11.9.5)IRM 4.26.11.9.5Internal Revenue Manual, irs.gov. |
| Letter 4280Form 8300 examination closed, no issue | Business | No response required. |
| Letter 4595Form 8300 penalty proposed, no intentional disregard: 30-day letter with no pre-assessment appeal | Business | 30 days to agree on Form 14141 or to write and ask for a manager meeting; then assessed, with appeal after… |
| Letter 4596Form 8300 intentional disregard penalty proposed: 30-day letter with pre-assessment Appeals | Business | 30 days: small case request if $25,000 or less (Form 12203 acceptable), formal written protest in duplicate… |
| Letter 5376Full or partial claim disallowance, employment tax: 30-day letter | Payer | 30 days to protest to Appeals (IRM 4.23.13.3.1.2; 4.23.13.2.2(11))IRM 4.23.13.3.1.2Internal Revenue Manual, irs.govIRM 4.23.13.2.2(11)Internal Revenue Manual, irs.gov. |
| Letter 5154Abatement request closed: allowed or denied, no Appeals beyond the group | Payer | No statutory deadline. |
| Letter 917Reply to a request to reconsider a disallowed claim; not a certified disallowance | Payer | No new deadline. |
| Letter 570Claim for refund allowed in full | Payer | No response required. |
| Letter 105-C / 106-CCampus claim disallowance in full (105-C) or in part (106-C) | Payer | The two-year period to file suit under IRC 6532IRC 6532Internal Revenue Code, Cornell LII runs from a certified notice of disallowance and "is not… |
| CP 108Problem with your federal tax deposit: the IRS could not tell what an EFTPS payment was for | Payer | No printed deadline; reply "as soon as possible." |
| CP 267 / CP 268Notice of excess credit: more deposits posted than the return claimed; Q- freeze | Payer | 15 cycles from the return posting. |
| Letter 31CDuplicate returns filed; explanation requested | Payer | 40-day suspense (IRM 21.7.9.4.1.4(3))IRM 21.7.9.4.1.4(3)Internal Revenue Manual, irs.gov. |
| Letter 4384CWrong instrument: file a signed original, or use the X form | Payer | 45-day suspense (IRM 21.7.9.4.1.6.1(3))IRM 21.7.9.4.1.6.1(3)Internal Revenue Manual, irs.gov. |
| Letter 4402CIdentity theft closing letter for a non-tax-related income claim | Payee | No response required. |
| Letter 4674CIdentity Theft Post-Adjustment Victim Notification Letter | Payee | No response required. |
| CP 565 A / CP 565 BITIN assigned, renewed, or status notice, with an Active or Inactive indicator | Payee | No response required. |
| CP 566ITIN application suspended: additional information required | Payee | 120 days for the applicant to respond; systemic reject at day 140. |
| CP 567ITIN application rejected, or ITIN revoked | Payee | No deadline stated. |
| CP 574 / Letter 6628ITIN application hard reject: no filing requirement on the attached return | Payee | No deadline stated. |
| Letter 608-CRequest for information on a dishonored payment penalty (IRC 6657)IRC 6657Internal Revenue Code, Cornell LII | Payer | Reply by the date on the letter. |
| CP215 (Form 8278 penalties)Notice of Penalty Charge, business: the bill for an assessable penalty, with no proposal stage before it | Payer | Pay by the date shown, or file a written appeal request; "Appeals currently provides a prepayment, post… |
| Letter 5071CIdentity verification before a return is processed, with an online option | Individual taxpayer | No fixed deadline is printed, but the refund and the return stay frozen until verification is complete, and… |
| Letter 4883CIdentity verification before a return is processed, by telephone | Individual taxpayer | The letter sets no response date, but the return does not process and no refund issues until the call is… |
| Letter 5747CIdentity verification in person only | Individual taxpayer | No date is printed; the return stays unprocessed and the refund held until the visit. |
| Letters 6330C and 6331CPilot versions of the identity-verification letters | Individual taxpayer | None printed; the return and any refund wait for verification, and no account information is released while… |
| Letter 950-D (and 950-C)The employment tax 30-day letter after an unagreed examination | Payer or employer whose employment tax examination, including a backup withholding examination, ended without a signed agreement | Thirty days from the letter date to sign the agreement, submit a protest or small case request, or ask for… |
| Letter 3523Notice of determination of worker classification: 90 days to petition the Tax Court | Employer or payer whose examination reclassified workers as employees or denied section 530 relief, and who did not reach agreement | Ninety days from the date of the letter to file a petition with the United States Tax Court (150 days if… |
| CP 161Balance due on a business return, no math error | Any business filer, including a payer whose Form 945 posted with less credit than it claimed | Pay by the date on the notice to avoid further interest and the failure-to-pay penalty; the… |
| CP210 and CP220Examination or data processing adjustment to a business account | Payers after a Form 945 compliance check or examination, after a credit transfer that recomputed penalties, or after any adjustment to a business module | A CP 220 with a balance due is a notice and demand: 21 calendar days to pay without additional interest. |
| CP 225A missing payment was found and applied | Any business taxpayer whose payment tracer or credit transfer request has been worked | If a balance remains, the notice-and-demand window applies to it. |
| CP 260A payment previously applied to your account was reversed | Business taxpayers from whose module a credit was moved, including the 941 module that had absorbed a stray Form 945 deposit | The balance shown is due on the notice-and-demand terms: 21 calendar days to pay without additional interest. |
| CP 259First notice that a business return has not been filed | Businesses with an open filing requirement and no return posted, including a Form 945 requirement left open after withholding stopped | The notice gives a response date. |
| CP 134B and CP 134RFederal tax deposits credited differ from the deposits reported | Business filers whose return claimed more or less in deposits than the IRS has posted, including Form 945 filers | A CP 134B balance is due on notice-and-demand terms. |
| Letters 63C and 62CA payee told the IRS your W-2 or 1099-R never arrived: 10 days to respond to the payee | Employers and payers of pensions, annuities and IRA distributions, after a payee calls the IRS about a missing, lost or incorrect Form W-2 or Form 1099-R | 10 calendar days from receipt, to respond to the payee, not to the IRS. |
How these notices connect
The sequence, when things go wrong: CP2100 (the mismatch list) → B-Notices to payees → Notice 972CG a year later (the proposed penalty) → CP15 or CP215 if it isn't waived (the assessment) → CP504 if it isn't paid (collection). Everything else on this page is a branch off that trunk, or the Form 945 and underreporter tracks that run beside it.
The sequence when a TIN is wrong
CP2100 / CP2100AThe mismatch list, spring and fall.
B-NoticeYou to the payee, within 15 business days.
Backup withholding24% from business day 30 if no response.
Notice 972CGThe proposed penalty, about a year later. 45 days to respond.
CP15 / CP215The assessment if not waived, then CP504 if unpaid.