A CP2100 or CP2100A notice goes to businesses, not individuals. It means some information returns you filed, such as Forms 1099-NEC, 1099-MISC or 1099-INT, show a payee name and taxpayer identification number (TIN) combination that is missing or doesn't match IRS records. The notice comes with a list of those payees. It's routine, especially for businesses that file many 1099s, but it does set off deadlines. You may need to send letters called "B-notices" to payees and start backup withholding on future payments.
Why you got a CP2100 or CP2100A
When you file information returns, the IRS checks each payee's name and TIN against its own records and those of the Social Security Administration. A notice is triggered when a TIN is:
- Missing from the information return.
- Obviously incorrect, meaning not nine digits or containing something other than numbers.
- Incorrect or not currently issued, meaning the name and number don't match IRS records.
CP2100 vs. CP2100A. The IRS issues a CP2100 when a payer has filed 50 or more information returns with errors, and a CP2100A when there are fewer than 50. The instructions are the same. The IRS sends these notices twice a year, in October and the following April.
What the CP2100 says
The notice explains what to do and includes a list of payee accounts with missing, incorrect or not-currently-issued TINs. Look at:
- The notice date (or the date you received it, if later). Your B-notice deadlines run from whichever is later.
- Each listed payee, with the name, TIN and account number you reported.
- Whether a payee is on the list for the first or second time within three calendar years. That decides which B-notice you send.
What to do
For missing or obviously incorrect TINs
- Start backup withholding now on that payee if you aren't already. The IRS says this applies even to one-time payments.
- Ask the payee for their TIN. To avoid a penalty for leaving the TIN off an information return, you must make up to three requests: an initial one, a first annual and a second annual solicitation.
- Keep withholding on payments until you receive the TIN.
For TINs that don't match IRS records
- Compare the IRS list with your records. If your records are different, the mismatch may come from a recent update, an error in what you filed, or an IRS processing error. In that case, just correct or update your records.
- If your records match the list, send a B-notice within 15 business days from the date of the notice or the date you received it, whichever is later. Date the B-notice no later than 30 business days after that same date.
- Send the right one:
- First B-notice, if this is the first time in three calendar years the payee account has been listed: send the First "B" Notice with a Form W-9 and, optionally, a reply envelope.
- Second B-notice, if it's the second time within three calendar years: send the Second "B" Notice without a Form W-9. The payee must validate their TIN with the SSA (for an SSN) or the IRS (for an EIN, using Letter 147C).
- Mark the outside envelope "IMPORTANT TAX INFORMATION ENCLOSED" or "IMPORTANT TAX RETURN DOCUMENT ENCLOSED."
- Start backup withholding if the payee doesn't respond. For a First B-notice, begin no later than 30 business days after the CP2100 date (or receipt date, if later). For a Second B-notice, begin if you don't receive the validation by the 30th business day after the date of the Second B-notice.
- Stop backup withholding no later than 30 calendar days after you receive a signed Form W-9 (First B-notice) or the required validation (Second B-notice).
- Update your records with the corrected information for future information returns. Don't send the Form W-9 to the IRS.
The IRS says not to call or write to tell it you corrected your records. Publication 1281 also says you don't need to file a corrected information return unless you're changing the dollar amount reported. You can't collect the TIN by phone; it must come back in writing as described.
Backup withholding basics
- Rate: The current backup withholding rate is 24% of the payments you make to the payee (IRS, 2026; Publication 1281 says this rate has applied to payments after December 31, 2017).
- Depositing: Deposit backup withholding under your monthly or semiweekly deposit schedule, as explained in Publication 15 (Circular E).
- Reporting: Report it on Form 945, Annual Return of Withheld Federal Income Tax, using the same name and EIN you used on the information returns. If you use a paying agent, don't put their name on Form 945.
Third and later notices
Publication 1281 says you can generally ignore a third or later notice for the same account if you completed the First and Second B-notice steps and the incorrect name, TIN and account number are unchanged. If the same payee shows up with a different name/TIN combination, treat it as a first notice.
If you're a payee who got a B-notice
If a business sent you a B-notice, it means the name and TIN you gave them don't match IRS records. Respond by the date on the letter. For a First B-notice, return a signed Form W-9 with your correct name and number. For a Second B-notice, you must provide a copy of your Social Security card (or IRS Letter 147C for an EIN). Publication 1281's sample notices warn that the IRS may charge a $50 penalty for failing to give a payer your correct name and TIN, and backup withholding can reduce your payments until it's fixed.
What happens if you ignore it
Payers who don't follow the B-notice and solicitation rules can face IRS penalties for filing information returns with missing or incorrect TINs. Publication 1281 mentions the IRS may send a Proposed Penalty Notice (Notice 972CG). Following the steps above, and keeping records of your B-notices and solicitations, is how you show you acted correctly. If you're unsure, a CPA or enrolled agent who handles payroll and information reporting can help.
Is this notice real?
A genuine CP2100 or CP2100A is mailed to your business address of record. Check that the payees on the list are ones you actually paid. For a copy or questions, the IRS lists 866-455-7438 (toll-free) or 304-263-8700, Monday through Friday, 8:30 a.m. to 4:30 p.m. ET. Keep your business address current with Form 8822-B so you receive future notices. See our IRS scams guide.
Frequently asked questions
Where do I get the B-notice letters?
Publication 1281 contains copies of the First and Second "B" Notices, along with Form W-9 and instructions.
Can I check TINs before I file 1099s?
Yes. The IRS says payers of most Forms 1099 can apply to use its TIN Matching program to check payee names and TINs before filing.
Do I need to tell the IRS when a payee sends a corrected TIN?
No. Correct your records and stop backup withholding on future payments to that payee. Don't send the information to the IRS.
What if the payee has applied for a TIN but doesn't have one yet?
Publication 1281 says the 60-day "awaiting TIN" exemption applies only to interest and dividend payments and certain payments on readily tradable instruments. Other payments, such as nonemployee compensation, are subject to backup withholding right away.
Where can I learn more about running a small business's tax obligations?
See our small business owners hub and our page on the CP575 EIN confirmation notice.
Sources
IRSV.com is an independent guide and is not affiliated with the IRS. This page is general information, not tax or legal advice. Rules change; confirm details on IRS.gov or with a tax professional. Found an error? Tell us.