CP2100: Payee Tax IDs and Backup Withholding
Notice Instructions: Do not treat this as a no-action notice. Missing or obviously incorrect TINs and mismatched TINs have different withholding and notice instructions.
A contractor’s tax ID can become your business’s compliance problem. Compare the accounts before choosing the response.
CP2100 is sent to a payer when payee names or taxpayer identification numbers on information returns are missing or do not match IRS records. It includes affected accounts and may require backup withholding. The payer’s notice is distinct from the B notice sent to a payee.
Read The IRS Guidance For CP2100 · Source checked October 11, 2026.
Common Triggers
- Missing TIN
- Obviously incorrect TIN
- Name and TIN combination that does not match IRS records
What to Check Next
- Step 1: Compare the payee accounts on the notice with your business records.
- Step 2: For missing or obviously incorrect TINs, follow the IRS instructions to begin backup withholding immediately and request the TIN.
- Step 3: For mismatches that agree with your records, send the appropriate B notice; if the listing differs from your records, review the correction instructions.
- Step 4: Follow Publication 1281 for the applicable first or second notice and timing; retain account and response evidence.
- Step 5: Review withholding deposits and Form 945 reporting under the applicable instructions.
Common Questions About CP2100
- Who Receives CP2100?
- The payer that filed the affected information returns. A payee may separately receive a B notice from that payer.
- Is Form W-9 Always Enough?
- A First B Notice generally uses a signed Form W-9. A Second B Notice requires the specified name/TIN validation. Follow the applicable instructions; do not repeat the first-notice response automatically.
- Must I Tell The IRS That I Corrected My Records?
- Do not notify the IRS merely to say your records were corrected. Follow the notice’s comparison and withholding instructions; other reporting obligations may still apply.
- What Is The Current Backup Withholding Rate?
- The IRS lists 24%. Whether and when it applies depends on the account and the missing-TIN or mismatch rules.
Additional Resources
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