CP2100 and CP2100A Notices: Missing or Incorrect Payee TINs

CP2100 and CP2100A are notices to payers, meaning businesses and organizations that file information returns such as Forms 1099, not to the people being paid. The IRS sends them when the name and taxpayer identification number (TIN) on some of your information returns are missing, do not match IRS records, or are not currently issued. If you pay contractors, landlords or vendors and file 1099s, you may eventually receive one. What you do next depends on the kind of problem.

What the notice means

The notice reports that some payee name and TIN combinations do not agree with IRS records. The IRS lists the TINs, and your job is to work out which type of problem each represents.

The two kinds of problems

Missing or obviously incorrect TINs. The IRS describes an obviously incorrect TIN as one that is not nine digits or contains non-numeric characters. For these, start backup withholding immediately and request the TIN from the payee. To avoid the penalty for leaving a TIN off an information return, the IRS says you may need to ask up to three times: an initial request, a first annual request and a second annual request.

TIN mismatches. Compare the notice with your payee records.

• If they match, send the appropriate "B" notice to the payee right away. If the payee does not respond, begin backup withholding on future payments no later than 30 business days after you received the notice. Stop backup withholding within 30 calendar days of receiving a corrected TIN.
• If they do not match, the IRS says to correct or update your own records. Do not contact the IRS to report the correction.

First and second B notices

The IRS B program page explains the two payee notices. You send the first B notice, together with a Form W-9, the first time a payee appears on a CP2100 or CP2100A. You send the second B notice if the same payee appears on a CP2100 or CP2100A a second time within three years. To end backup withholding after the first B notice, the payee gives you a properly completed, signed Form W-9 or an acceptable substitute. After a second B notice, the payee must instead provide a copy of their Social Security card, or IRS Letter 147C for an EIN. Publication 1281 has the detailed rules, so confirm the current version before acting on a repeat notice.

Backup withholding

The IRS page gives the current backup withholding rate as 24 percent of payments to the payee (as of the IRS page reviewed in 2026). You report amounts withheld on Form 945, using the same name and EIN as your information returns, and you deposit under the monthly or semiweekly schedule. Publication 1281 is the IRS's detailed guide to backup withholding on missing and incorrect TINs and to the B notices.

Steps to take

1. Find the notice and the TIN list. If you cannot, the IRS offers a payer phone line to request a copy.
2. Sort each payee into missing, obviously incorrect or mismatched.
3. Send B notices and start backup withholding where required, and track the deadlines.
4. Fix your own records when a payee supplies a corrected TIN, and keep the paperwork. Collect a signed Form W-9 before the first payment to new payees.
5. Consider the IRS TIN Matching program. The IRS notes that most Form 1099 payers can apply to check names and TINs before filing.
6. Keep your address current with Form 8822-B so you receive the notice.

Penalties

The page mentions a penalty for not including a TIN on an information return, which asking for the TIN up to three times helps you avoid, but gives no amounts. See information return penalties for 1099 and W-2.

Common mistakes

• Treating the notice as an IRS error and doing nothing.
• Missing the time allowed to send the B notice.
• Calling the IRS to report a corrected TIN, which the IRS says not to do.
• Withholding but forgetting to deposit and report on Form 945.

When to involve a CPA

Backup withholding introduces deposits and a separate return. A CPA can set up the process, send the notices on time and make sure Form 945 is filed, and with a signed Form 2848 can speak with the IRS for your business. See contractors and Form 1099-NEC and Forms 1099-NEC and 1099-K. Our bookkeeping and payroll services can handle vendor setup and year-end filings.

How we can help

We can review a CP2100 or CP2100A list, sort the payees, prepare the B notices and manage backup withholding. See our IRS representation services or contact us.

Frequently asked questions

General information only, not tax, legal or accounting advice for your situation. Rules, limits and deadlines change; confirm the current rules with the official source or a qualified professional before you act. Reading this page does not create a professional relationship with CPA Tax Payroll and Accounting Corp.