Your bank is asking you to fill out a Form W-9 because federal law requires it to have your taxpayer identification number on file before it pays you any reportable income and reports that income to the IRS. Interest on a savings account, dividends from a brokerage, a sign-up bonus, even a promotional prize can create a reporting obligation, and the W-9 is how the bank collects the information it needs to meet it. The request is routine. It is not a sign of an audit, a fraud investigation, or a problem with your account by itself.
That said, the request is always tied to something specific. Figuring out which trigger applies to you usually clears up the confusion and tells you what, if anything, you need to do beyond returning the form.
Common Reasons a Bank Requests a W-9
You Opened a New Account
The most common trigger is simply opening an account that can earn income. Savings accounts, money market accounts, certificates of deposit, and brokerage accounts can all generate interest or dividends the bank must report to the IRS once they reach $10 for the year.1Internal Revenue Service. Instructions for Forms 1099-INT and 1099-OID When you open a new account or make an investment, you have to furnish your TIN in writing and certify it under penalty of perjury.2Internal Revenue Service. Backup Withholding Banks collect the W-9 up front so the information is ready before any reportable income is paid.
The IRS Flagged a Name or TIN Mismatch
If the name and TIN your bank has on file don’t match IRS records, the IRS sends the bank a CP2100 or CP2100A notice, known in the industry as a “B-Notice.”3Internal Revenue Service. Backup Withholding B Program Mismatches usually come from ordinary things: a name change after marriage, a typo at account setup, or a legal name that differs from the shortened version you normally use.
Once a B-Notice arrives, the bank must send you a First B-Notice with a fresh W-9 within 15 business days.4Internal Revenue Service. Backup Withholding for Missing and Incorrect Name/TINs Don’t ignore it. Until the bank receives a corrected W-9, it is required to start backup withholding on the account’s earnings.
Ownership or Structure Changed
Adding or removing a joint owner changes which TIN is associated with the reported income, so the bank needs an updated W-9 to make sure the right person receives the year-end tax forms. The same goes for converting a personal account to a custodial account for a minor, where the W-9 would carry the minor’s Social Security Number rather than the parent’s.
Business accounts trigger W-9 requests for parallel reasons. A change in authorized signers, or restructuring the entity (say, converting a sole proprietorship to an LLC), can require a new form so the bank has the current EIN and correct tax classification.
You Hold a Business or Investment Account
Banks are especially thorough about W-9s for commercial and investment accounts. When an LLC or corporation opens a business checking account, the W-9 confirms the entity’s EIN and how it should be classified for tax purposes, which determines how the bank reports payments at year-end. Brokerage accounts need a W-9 so the bank can report stock sale proceeds and dividend distributions on Forms 1099-B and 1099-DIV.5Internal Revenue Service. Instructions for Form 1099-B (2026)
You’re Opening or Managing a Trust or Estate Account
For a bank account held by a trust or estate, the W-9 should list the trust or estate’s name and its own EIN, not the trustee’s or personal representative’s Social Security Number. The IRS instructions are explicit: provide the legal entity’s TIN unless the entity itself isn’t named in the account title.6Internal Revenue Service. Form W-9 (Rev. March 2024) Request for Taxpayer Identification Number and Certification Getting this wrong is one of the more common ways a B-Notice gets generated later.
What the Form Actually Asks For
The W-9’s full name is “Request for Taxpayer Identification Number and Certification.”6Internal Revenue Service. Form W-9 (Rev. March 2024) Request for Taxpayer Identification Number and Certification You provide your legal name, your address, and your taxpayer identification number. For individuals, the TIN is your Social Security Number. For businesses, it’s the Employer Identification Number. You also check a box identifying your federal tax classification: individual, corporation, partnership, LLC, and so on.
You sign the form under penalty of perjury, certifying three things: the TIN is correct, you are a U.S. person for tax purposes (which includes U.S. citizens and resident aliens), and you are not subject to backup withholding.6Internal Revenue Service. Form W-9 (Rev. March 2024) Request for Taxpayer Identification Number and Certification
There is also a field for a FATCA reporting exemption code. Certain entities, such as corporations, tax-exempt organizations, and registered securities dealers, are exempt from FATCA reporting and can enter a code identifying that status.7Internal Revenue Service. Instructions for the Requester of Form W-9 Most individual account holders leave that field blank.
What Happens If You Don’t Return It
Ignoring a W-9 request has real financial consequences. The main one is backup withholding: the bank takes 24% off the top of every reportable payment and sends it directly to the IRS.2Internal Revenue Service. Backup Withholding It applies to interest, dividends, brokerage proceeds, and other reportable income. It isn’t a penalty in the technical sense. It’s a forced tax prepayment, and the IRS keeps the money until you file your annual return and claim credit for it.
Backup withholding starts when any of these apply:8Internal Revenue Service. Topic No. 307, Backup Withholding
- You didn’t provide your TIN when required.
- The IRS notified the bank that the TIN you gave doesn’t match its records.
- The IRS notified the bank to begin withholding because you previously underreported interest or dividend income (the IRS sends four notices over at least 120 days before this kicks in).
- You didn’t certify that you’re not subject to backup withholding.
Beyond withholding, banks may freeze or restrict accounts when a customer refuses to submit a W-9. The IRS instructions require banks to presume that a payee who hasn’t submitted a W-9 or similar certification of non-foreign status is subject to withholding under both backup withholding rules and FATCA reporting rules.9Internal Revenue Service. Instructions for the Requester of Form W-9 Individual bank policies vary, but the regulatory pressure to verify customer identity is significant enough that stonewalling can lead to account limitations.
If backup withholding has already hit your account, the money isn’t gone. Your year-end Form 1099 will show the amount withheld, and you report that figure as federal income tax withheld on your Form 1040. If the withholding exceeds your actual tax liability, you get the difference back as a refund.8Internal Revenue Service. Topic No. 307, Backup Withholding Partners in partnerships and shareholders in S corporations claim backup withholding on their individual returns, not the entity’s.
If You’re Not a U.S. Person, Don’t Complete a W-9
The W-9 is only for U.S. persons. If you are a foreign national, a nonresident alien, or a foreign entity, don’t fill one out. Your bank should instead ask you to complete Form W-8BEN (for individuals) or another form in the W-8 family (for entities).10Internal Revenue Service. About Form W-8 BEN, Certificate of Foreign Status of Beneficial Owner for United States Tax Withholding and Reporting (Individuals) The W-8BEN establishes your foreign status and determines whether a tax treaty reduces the withholding rate on U.S.-source income. If a W-9 lands in your inbox and you aren’t a U.S. person, tell the bank so it can send the right form.
Make Sure the Request Is Really From Your Bank
A W-9 asks for your name, address, and Social Security Number or EIN, which makes it an obvious target for phishing. Scammers send emails and texts that look like they’re from your bank, claim there’s a problem with your account, and push you to “update” your W-9 through a link. The FTC flags the usual signs: generic greetings, urgent language about account suspension, and links asking you to update personal or financial information.11Consumer Advice (FTC). How To Recognize and Avoid Phishing Scams
A real bank won’t email you a link to submit your Social Security Number. If you aren’t sure a W-9 request is genuine, call your bank using the number on the back of your debit card or on its official website. You can usually submit a completed W-9 in person at a branch, through the bank’s secure online portal, or by mail to the department the bank designates. Never send an unencrypted W-9 by email.