CP2100 / CP2100A · Notice 972CG · CP15 · CP215 · CP504 / CP504B · C-Notice · CP539 · Letter 147C · CP 575 · CP136 / Form 945 deposit notices · Letter 1948C
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). Every step after the first is avoidable by answering the one before it on time.
CP2100 / CP2100A Notice of possibly incorrect or missing payee TINs
Sent to: Payer
What it is. Lists the information returns you filed whose name/TIN combinations did not match IRS records or had no TIN. CP2100A is the version for fewer than 50 errors; larger filers get CP2100 (250 or more on electronic media). Issued twice a year, spring and fall, for the prior filing season. It is not a bill and not a penalty.
Deadline. Mail B-Notices within 15 business days of the notice date or receipt (later of the two); begin 24% backup withholding no later than 30 business days after the notice date for payees who don't respond.
What to do. Compare each listed account to your records, skip accounts already corrected, determine first vs. second notice, mail the letters, set the withholding flags, log everything.
Notice 972CG Notice of proposed civil penalty for information returns
Sent to: Payer
What it is. Proposes penalties under IRC 6721 for information returns filed late, on paper when e-filing was required, or with missing or incorrect TINs. Arrives 12 to 18 months after the filing season it covers. Lists each return type, the failure, the count and the proposed amount.
Deadline. 45 days from the notice date (60 if you're outside the U.S.) to agree, agree in part, or request a waiver for reasonable cause. No response means assessment of the full amount.
What to do. Check the counts and tiers against your correction dates, pull the solicitation log and B-Notice records for every listed payee, write the reasonable-cause statement, sign under penalties of perjury, send with exhibits.
972CG guide · Penalty estimator · Reasonable-cause statement template
CP15 Notice of penalty charge (civil penalty assessed)
Sent to: Payer
What it is. Tells you the IRS has assessed a civil penalty that isn't subject to deficiency procedures and how much you owe. In the information-return context it usually follows a 972CG you didn't answer, or answered unsuccessfully. It carries appeal rights.
Deadline. Pay by the date shown, or request abatement / file an appeal, generally within 30 days of the notice date to preserve appeal rights before collection starts. Interest runs from the assessment.
What to do. If you never responded to the 972CG, you can still request abatement for reasonable cause with the same statement and exhibits; if you did respond and were denied, this is where you appeal.
CP215 Notice of penalty charge, business
Sent to: Payer
What it is. The business version of the penalty assessment notice for civil penalties, including information-return penalties under IRC 6721/6722. Shows the tax period, the penalty section, the amount and the payment due date.
Deadline. Pay or respond by the date on the notice; abatement requests and appeals follow the same route as CP15.
What to do. Match the assessment to the 972CG it came from; if the reasonable-cause statement was never sent, send it now with a request for abatement; if it was denied, appeal with any new documentation.
CP504 / CP504B Final notice, intent to levy
Sent to: Payer
What it is. A collection notice for an unpaid balance, including an assessed information-return penalty that was never paid or abated. It is a warning that the IRS may levy state tax refunds and, after further notices, other assets.
Deadline. Pay, set up a payment plan, or resolve the underlying penalty before the date shown. This is late in the process; a reasonable-cause request is still possible but collection is now running in parallel.
What to do. Find the original 972CG and CP15/CP215; if you have a reasonable-cause case that was never made, make it now and ask for a collection hold while it is considered.
C-Notice (backup withholding notification) IRS notice that a payee under-reported interest or dividends
Sent to: Payer (financial institutions)
What it is. The IRS tells a payer of interest and dividends to start backup withholding on a specific payee because that payee under-reported that income on their own return. Unlike a B-Notice, the payer cannot stop withholding on the payee's say-so; only the IRS can lift it.
Deadline. Begin 24% backup withholding on interest and dividend payments to that payee by the date in the notice and continue until the IRS notifies you to stop.
What to do. Flag the account in the core system; do not accept a W-9 as a cure; the payee resolves it with the IRS directly.
CP539 (to the payee) IRS notification to a taxpayer that they are subject to backup withholding
Sent to: Payee
What it is. Sent to an individual payee, not to you, when the IRS decides they under-reported interest or dividends. The payee's payers receive the corresponding C-Notice. Payees sometimes forward this to a payer asking what to do.
Deadline. The payee has the response window on the notice to dispute it with the IRS. Nothing for the payer to do beyond following its own C-Notice.
What to do. Tell the payee the withholding is required until the IRS releases it and that the amounts are credited on their return.
Letter 147C EIN verification letter
Sent to: Payee (business)
What it is. Issued by the IRS at a business's request (Business & Specialty Tax Line, 1-800-829-4933) confirming the legal name and EIN on file. It is what a payee provides in response to a Second B-Notice when the TIN is an EIN, and the document to match a W-9's line 1 against when a legal name is in doubt.
Deadline. No deadline of its own; the payee needs it within the payer's 30-business-day B-Notice window.
What to do. Payers: accept a copy as the validation after a Second B-Notice, and use the legal name on it exactly. Payees: request it as soon as the Second B-Notice arrives; the IRS mails or faxes it to the address or number on file.
CP 575 EIN assignment notice
Sent to: Payee (business)
What it is. The notice the IRS issues when it assigns an EIN, showing the exact legal name tied to the number. Issued once; a business that has lost it requests a Letter 147C instead.
Deadline. None. It's a reference document.
What to do. Use the legal name on it for line 1 of the W-9; payers can ask for a copy when a new vendor's name and EIN don't match.
CP136 / Form 945 deposit notices Deposit-frequency and Form 945 correspondence
Sent to: Payer
What it is. Notices about your nonpayroll withholding account: which deposit schedule applies for the coming year (based on the lookback period), missing Form 945, or deposits that don't match the return.
Deadline. Per the notice; a missing-945 notice typically gives 30 days.
What to do. Reconcile backup withholding withheld, deposited and reported; file or correct Form 945; adjust the deposit schedule if the notice changes it.
Letter 1948C (and similar penalty-response letters) IRS reply to a penalty abatement or reasonable-cause request
Sent to: Payer
What it is. Correspondence acknowledging or deciding a request you made about a penalty: received and under review, granted in full or part, or denied with appeal rights. The letter number varies; the substance is the IRS's answer to your 972CG or CP15 response.
Deadline. If denied, the appeal window stated in the letter (typically 30 days).
What to do. Read the reason for any denial; a denial for 'insufficient documentation' is often cured by resending the solicitation log with dates and methods.