What the IRS says: “Information returns you filed (1099s) contain payee name/TIN combinations that don't match IRS records — backup withholding rules may apply.” Here’s what it actually means, your deadline, and exactly how to respond.
The CP2100/2100A tells payers: some of your 1099 payees' TINs don't match. Your legal duties have a clock: send first B notices (with W-9) to affected payees within 15 business days, and start 24% backup withholding on those who don't respond within 30 days. Documenting this process is your penalty shield.
Notice family: Business Notices — Payroll deposits, information returns and business balance dues. Same escalation logic as individual notices, tighter timelines, and penalties that compound per form — worth responding to precisely.
15 days — business days to send first B notices to affected payees.
Counted in calendar days from the notice date. The exact respond-by date printed on your notice always controls — check page 1.
Compare each listed payee against your W-9 files — if the W-9 matches what you filed, no B notice needed (keep the proof)
Mismatches: mail the first B notice + W-9 within 15 business days
No W-9 back in 30 days: begin 24% backup withholding and remit it
Second CP2100 for the same payee in 3 years: second B notice (payee must contact SSA/IRS, not just re-sign a W-9)
There's no letter to the IRS unless you're contesting a proposed penalty (972CG) later — the response is the documented B-notice process itself. Run it precisely and keep the mailing log.
Describe the notice and your side of it — use placeholders, never your SSN or account numbers (the letter keeps [YOUR NAME]-style fields so you fill in the real details privately before mailing). A mail-ready draft with an enclosure checklist comes back in ~20 seconds.
Your IRS response letter draft will appear here.
Information returns you filed (1099s) contain payee name/TIN combinations that don't match IRS records — backup withholding rules may apply. In practice: The CP2100/2100A tells payers: some of your 1099 payees' TINs don't match. Your legal duties have a clock: send first B notices (with W-9) to affected payees within 15 business days, and start 24% backup withholding on those who don't respond within 30 days. Documenting this process is your penalty shield.
You generally have 15 days — business days to send first B notices to affected payees. The respond-by date printed on your own notice always controls.
There's no letter to the IRS unless you're contesting a proposed penalty (972CG) later — the response is the documented B-notice process itself. Run it precisely and keep the mailing log.