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Has Your Client Received a Notice CP2100 from the IRS?

By S. Miguel Reyna, CPA

The IRS uses Notice CP2100 and CP2100A to inform a payer that there are problems with taxpayer information numbers on Forms 1099 that have been filed and that the payer may be responsible for backup withholding. The payer needs to know how to respond to these notices because failure to follow the rules can result in penalties for filing incorrect information returns and in possible liability for uncollected taxes.

Large volume filers with 250 or more erroneous Forms 1099 receive the CP2100 Notices electronically; those with 50-249 receive the CP2100 Notices on paper, and those with less than 50 receive paper Notice CP2100A. These notices include lists of errors such as missing TINs, those that don’t match the taxpayer and those in an incorrect format; e.g., a letter instead of a number or too many digits. 

When the first Notice CP2100 is received, the payer should send the first B-Notice (backup withholding notice) and a Form W-9, Request for Taxpayer Identification Number, to a payee within 15 business days from the “basis date” of the CP2100 (date on notice or date the payer received the notice in the mail, whichever is later). The payee needs to fill out the W-9 and return it to the payer.

If a second Notice CP2100 is received within three calendar years, the payer needs to send the second B-Notice within 15 business days from the basis date and clearly mark "IMPORTANT TAX INFORMATION ENCLOSED" on the outside of the mailing envelope. The second B-Notice tells the payee to contact the IRS or the Social Security Administration to obtain the correct name/TIN combination. 

If a payee does not respond within 30 days of the first or second B-Notice, the payer must begin backup withholding at a rate of 28 percent. The withholding continues until no later than 30 days after the payee submits a TIN that is able to be validated.

There are additional steps to be taken by the payer, and further information is available in IRS Pub 1281 ( and on the IRS website at,-State-%26-Local-Governments/Backup-Withholding.

Have you had experience with this? Have any of your clients been required to backup withhold?



hello, what if the payer failed to proceed within the first 15 days of sending the B notices or start the BHW. Can the payer proceed with same CP2100A notice and send late notices to payees within same calendar year?

Patricia Jones

We received a 2100A for a then contractor for 2013 & 2014. The contractor has been an employee since 2014 W-9 is currently on file. Is there any further action required?


Using the information provided on a W-9, I filed a 1099-Misc for a contract laborer. She no longer works for us and has moved with no forwarding address. We received a CP-2100A but I am unable to contact the laborer. As she is no longer working for us, I cannot begin backup withholding either. What should I do?

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