If your bank is asking about backup withholding, it’s because federal law requires it to verify your taxpayer identification number and tax-reporting status before paying you interest, dividends, or other reportable income. When something about that information is missing, unverified, or flagged by the IRS, the bank must withhold 24% of those payments and send it to the Treasury.1Internal Revenue Service. Topic No. 307 – Backup Withholding The letter is not an accusation and not a penalty. The bank is the party under the legal obligation, and it’s contacting you because your response is usually all that’s needed to keep withholding from starting.
Which of the Four Triggers Applies to You
Federal law lists exactly four situations that require a bank to begin backup withholding. The reason your bank reached out is one of them, and identifying which one tells you what to do.2Internal Revenue Service. Backup Withholding
- You never gave the bank a TIN. When you opened the account, the bank needed your Social Security number or other taxpayer identification number so it could report your income to the IRS. If that number is missing, withholding is required.
- The TIN on your account doesn’t match IRS records. The IRS compares the name and TIN your bank reports against its own database. When they don’t line up, the IRS sends the bank a notice (CP2100 or CP2100A) listing the mismatched accounts, and the bank must act on it.3Internal Revenue Service. Understanding Your CP2100 or CP2100A Notice
- You never certified your status. For interest- or dividend-earning accounts, you must certify under penalty of perjury that your TIN is correct and that you aren’t currently subject to backup withholding. That certification happens on Form W-9. If you never signed one, or didn’t return it when the bank asked, withholding must begin.4Internal Revenue Service. Form W-9 (Rev. March 2024)
- The IRS flagged you for underreporting past interest or dividend income. This is the most serious trigger and requires a different fix than the others.
The first three are easily the most common reasons a routine letter goes out, and all three are usually fixed with a single form.
What to Do Right Now
For the first three triggers, the fix is to complete IRS Form W-9 and return it to your bank. The form asks for your name exactly as it appears on your Social Security card, your TIN, and your signature certifying that the information is correct and that you aren’t subject to backup withholding for underreporting. Once the bank has a valid W-9 on file, the withholding obligation goes away.2Internal Revenue Service. Backup Withholding
Before you sign, check that the name on the W-9 matches your Social Security card character for character. The most common cause of a mismatch is a name change (marriage, divorce) that was updated with the bank but not with the Social Security Administration, or the reverse. The IRS requires that your name and SSN agree with your Social Security card.5Internal Revenue Service. Name Changes and Social Security Number Matching Issues A typo at account opening will do it too. Fixing the W-9 without fixing the underlying mismatch just produces another notice later.
If you ignore the request, the consequences are automatic. The bank has no discretion. Without your completed form, it must start withholding 24% from every reportable payment, and the withholding continues indefinitely until you provide the documentation. There is no expiration.
If the Letter Is a B Notice
When the request is tied to a TIN mismatch, your bank is working through a sequence the IRS calls the “B” program, and the steps escalate.
The first contact is a First B Notice with a blank Form W-9 attached. Fill out the W-9 with the correct name and TIN and send it back. If you don’t, the bank must begin withholding no later than 30 business days after it received the CP2100 notice from the IRS.3Internal Revenue Service. Understanding Your CP2100 or CP2100A Notice Once the bank receives your corrected TIN, it must stop withholding within 30 calendar days.
If a mismatch for the same account shows up again on a CP2100 notice within three years, you’ll get a Second B Notice. This time a W-9 alone isn’t enough. You’ll need to send a copy of your Social Security card, or, if the account uses an Employer Identification Number, a Letter 147C from the IRS confirming that your name and EIN match.6Internal Revenue Service. Backup Withholding “B” Program The documentation requirement exists because you’ve already had one chance to fix the problem.
If the IRS Ordered the Withholding for Underreporting
The fourth trigger is different in both origin and cure. Before the IRS tells your bank to start withholding, it sends you at least four notices over a minimum of 120 days asking you to address underreported interest or dividend income.1Internal Revenue Service. Topic No. 307 – Backup Withholding If you don’t respond, the IRS issues a final notice (CP 539) telling you backup withholding is in effect, and sends a separate notice (CP 543) to your bank directing it to begin withholding within 30 business days.7Internal Revenue Service. 5.19.3 Backup Withholding Program
In this situation, your bank cannot stop withholding on its own. Submitting a new W-9 won’t release it, because the order came directly from the IRS. You have to resolve the underlying issue with the IRS first, which usually means showing that the underreporting didn’t happen, filing the missing returns, or paying the tax plus any related penalties and interest. Once the IRS is satisfied, it notifies both you and your bank that withholding should stop.
A W-9 still has a role here, with one change. If you sign one while you’re subject to an active underreporting notice, you must cross out the certification line that says you aren’t subject to backup withholding. You can certify that your TIN is correct, but you can’t certify exemption from withholding until the IRS clears you.4Internal Revenue Service. Form W-9 (Rev. March 2024)
What Gets Withheld and from What
The rate is a flat 24% off the gross payment. If your savings account earns $100 in interest and backup withholding is active, you receive $76 and the Treasury gets $24. The rule covers interest (Form 1099-INT), dividends (Form 1099-DIV), broker and barter exchange transactions, rents, royalties, and other payments reported on the 1099 series.1Internal Revenue Service. Topic No. 307 – Backup Withholding
Getting the Withheld Money Back
Money withheld under this program isn’t lost. It’s treated like any other tax payment made on your behalf, the same way paycheck withholding is. The amount is credited to your IRS account and you claim it when you file your annual return.
On Form 1040, backup withholding goes on Line 25b. The figure comes from Box 4 of the Form 1099 your bank sends you for the year.8Internal Revenue Service. 2025 Instructions for Form 1040 If the credit is larger than your actual tax for the year, the IRS refunds the difference. For most savers whose overall rate is below 24%, backup withholding tends to produce a refund.
The timing is the problem. You won’t see that money until you file and the refund is processed, which could be months after the withholding happened. That alone is a reason to respond to the bank’s request now rather than sort it out at tax time.
Who the Rule Doesn’t Apply To
Most individuals are not exempt. If you have a savings account, a brokerage account, or any other account that earns reportable income, backup withholding rules apply. Certain entities are generally exempt on payments like interest and dividends, including corporations, tax-exempt organizations under Section 501(a), IRAs, and federal and state government entities.4Internal Revenue Service. Form W-9 (Rev. March 2024) Even corporations lose that exemption for payment card and third-party network transactions.
Nonresident aliens generally aren’t subject to backup withholding either, because their U.S.-source income falls under a separate withholding regime with its own default rate and treaty reductions.9Internal Revenue Service. NRA Withholding If that’s your situation, your bank will ask for Form W-8BEN instead of a W-9.
A Note on State Withholding
A few states run their own backup withholding programs that stack on top of the federal 24%. If your bank’s notice mentions state withholding, check with your state tax agency, because the forms and resolution process can differ from the federal procedure.