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A second B-notice is not a repeat of the first. It triggers a different process, different requirements for your payee, and different rules around backup withholding. Getting the details wrong — especially sending a W-9 when you shouldn’t — doesn’t resolve the mismatch and can leave you exposed to IRS penalties.
This page covers who receives a second B-notice, exactly what it must include, how the response process works for individuals vs. businesses, and what to do if your payee doesn’t respond.
If you’re still at the beginning of this process — you just received a CP2100 and aren’t sure what it means — start with our CP2100 notice guide.
What Makes It a “Second” B-Notice
A payee receives a second B-notice if their name and TIN combination appeared on a CP2100 notice you received twice within a three calendar year period. (IRS Publication 1281, Q14)
That distinction matters in practice. A payee who appeared in December 2023 and again in January 2025 falls within the same three-calendar-year window (2023, 2024, 2025), even though the two appearances are only about 13 months apart.
You — not the IRS — are responsible for tracking this. The CP2100 does not indicate whether a given payee is on their first or second notice. You maintain that record, which is why internal documentation matters. (IRS Publication 1281, Q16)
What a Second B-Notice Must Include
A second B-notice must tell the payee they cannot resolve the mismatch by completing a new W-9. They need to certify their TIN directly with either the Social Security Administration (for individuals) or the IRS (for businesses and sole proprietors with EINs).
Required content:
- Notification that their name/TIN combination doesn’t match IRS records
- Clear statement that a W-9 alone is not sufficient
- Instructions specific to their situation — individual or business (see below)
- Do not include Form W-9
IRS Publication 1281, Appendix B provides sample second B-notice language. Use it, or adapt it — but don’t omit the key elements.
Your envelope must be marked “IMPORTANT TAX INFORMATION ENCLOSED” or “IMPORTANT TAX RETURN DOCUMENT ENCLOSED.” This is a hard IRS requirement, not a suggestion. (IRS Publication 1281, Q16)
What Your Payee Must Provide
The documentation required depends on whether your payee is an individual or a business entity.
Individuals (SSN holders): The payee must provide a copy of their Social Security card. Once you receive it, you have confirmation that the name and SSN match SSA records. (IRS Revenue Procedure 2014-43)
Businesses and sole proprietors (EIN holders): The payee must contact the IRS directly and obtain IRS Letter 147C — an EIN verification letter issued by the IRS Business & Specialty Tax Line. They then send a copy to you. (IRS — Backup Withholding “B” Program)
Do not accept a new Form W-9 in place of either of these. A self-certified W-9 does not satisfy the second B-notice requirement, and accepting one does not protect you from backup withholding obligations or penalty exposure.
Timing Requirements
Sending the notice: You have 15 business days from the CP2100 notice date — or the date you received it, whichever is later — to send the second B-notice. (IRS Publication 1281, Q15)
Beginning backup withholding: If the payee doesn’t respond within 30 business days of the CP2100 date (or receipt date, whichever is later), you must begin withholding 24% from future reportable payments and remitting it to the IRS. (IRS Publication 1281, Q19)
Stopping backup withholding: Once the payee provides a Social Security card (individuals) or IRS Letter 147C (businesses), stop backup withholding within 30 calendar days of receiving valid documentation. (IRS Publication 1281, Q19)
What Happens If the Payee Doesn’t Respond
If you receive no response and continue making payments to the payee, backup withholding at 24% is mandatory. Collect it, remit it to the IRS, and report it on Form 945 (Annual Return of Withheld Federal Income Tax).
If you receive no response and make no further payments to that payee, backup withholding is not required — but document that you sent the notice and received no response. That record matters if the IRS ever issues a 972CG penalty notice.
How This Fits Into Your Broader CP2100 Response
A second B-notice is one part of a larger process that starts the moment a CP2100 arrives. For a full breakdown — including first B-notice requirements, the backup withholding clock, common mistakes, and prevention strategies — see our complete CP2100 and B-notice guide.
How Tab Service Handles This for You
Generating compliant B-notice letters, hitting the 15-business-day window, and ensuring your envelopes are marked correctly is detail work that’s easy to get wrong under time pressure.
Tab Service generates and mails second B-notices as an add-on to the TAB1099 platform — producing the correct notice type with the required language and handling the mailing on your behalf.
Sources: IRS Publication 1281 — Backup Withholding for Missing and Incorrect Name/TINs (Rev. 12-2023); IRS Revenue Procedure 2014-43; IRS — Backup Withholding “B” Program; IRS Form 945.
