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IRS notice decoder · Business accounts and employer notices

CP2100 or CP2100A: payee names and TINs that don't match

A CP2100 or CP2100A lists payees whose name and TIN on your information returns are missing or don't match IRS records. It can start backup withholding.

By the Carry Forward Learning team Reviewed by Hunter Nottingham, JD, CPA

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CheckedOct 19, 2026

What a CP2100 means

A CP2100 or CP2100A goes to a payer, the business that filed information returns such as Forms 1099. The IRS says the payee name and taxpayer identification number on some of those returns are missing or don't match its records, and the notice lists them. source 1

The two are the same notice. The IRS says a CP2100 goes to payers with many returns in error and a CP2100A to payers with fewer; the instructions are identical. source 1

This is where backup withholding comes in. Depending on what you find, you may have to start holding back part of future payments to a payee and send that payee a B notice. We treat it as a records clean-up with a clock on it.

The date that counts

For missing or obviously incorrect TINs, the IRS says to start backup withholding immediately. For a mismatch that matches your records, you send a B notice, and if the payee doesn't answer, backup withholding on future payments must begin within a set number of business days after you received the CP2100 or CP2100A, as the IRS page states. source 1

Why people get one

  • A payee's TIN was missing, or obviously wrong, on a return you filed. source 1
  • A payee's name and TIN didn't match IRS records: a typo, a name change, or the wrong person's number. source 1
  • Your records were right but something changed on the way: a recent update, a filing error or an IRS processing error. source 1

First steps

  1. Compare each payee on the list with your own records. source 1
  2. For missing or obviously incorrect TINs, start backup withholding now and request the TIN: an initial request, then a first and second annual request. source 1
  3. Where your records match the notice, send the payee the right B notice; Publication 1281 has them. source 1
  4. Where your records don't match the notice, correct or update your own records. source 1
  5. Report any amounts withheld on Form 945 and deposit them on your usual schedule. source 1
  6. Make sure the IRS has your current mailing address; Form 8822-B changes it. source 1

What not to do

  • Don't contact the IRS to say you corrected your records, or send it a payee's corrected TIN. The IRS says just fix your records. source 1
  • Don't keep backup withholding going after a payee gives you a TIN; the IRS page sets a time limit for stopping. source 1
  • Don't ignore the list. Unfixed TIN problems can lead to information return penalties.
  • Don't act on a CP2100 that arrives by email or text with a link. The IRS mails these to your address of record.
  • Related 972CG The notice that proposes an information return penalty, a separate notice payers sometimes get.

Keep reading

Questions

What's the difference between a CP2100 and a CP2100A?

Only the number of returns in error. The IRS says the instructions are the same. source 1

When does the IRS send CP2100 notices?

The IRS page says twice a year, in October and the following April. source 1

If a payee gives me a corrected TIN, do I tell the IRS?

No. The IRS says correct your records and stop backup withholding on future payments to that payee. source 1

Can I check payee TINs before I file?

The IRS says payers of most Forms 1099 can apply for its TIN Matching program. source 1

Sources

  1. IRS, Understanding your CP2100 or CP2100A notice (updated July 27, 2026) (external site) checked Oct 19, 2026

Every rule on this page comes from the IRS page in the list, read on the date shown. Your notice itself is the final word on its own dates and amounts.