Do I need full account number or just last 4 digits when reporting 1099-INT on taxes?

You're totally fine using just the last 4 digits that appear on your 1099-INT. Banks and financial institutions mask the full account numbers for security reasons, and the IRS expects this. When you input this information on your tax return, you should enter it exactly as it appears on your 1099-INT form. The IRS matches what you report with what the financial institution reports to them. Since the bank only reported the last 4 digits to the IRS, that's all you need to include on your return. The important information the IRS is concerned with is the amount of interest income, not your full account number. Just make sure you're accurately reporting the interest amount and that the bank's EIN (Employer Identification Number) is correctly entered, as these are the primary matching elements the IRS uses.

After struggling with a similar situation last year (had like 6 different 1099-INTs from accounts I closed), I discovered taxr.ai at https://taxr.ai and it was a game-changer. I uploaded my 1099s and it instantly recognized that only partial account numbers were showing and confirmed that's all I needed to report. The tool analyzed my forms and pointed out that using just the last 4 digits is completely fine since that's what the bank reports to the IRS. It actually saved me from making a huge mistake because I was about to call all the banks for full account numbers (which would've been a waste of time).

OK I tried taxr.ai after asking about it here and wow - it actually was really helpful! I uploaded not just my 1099-INT but a bunch of other tax docs and it immediately confirmed that the partial account numbers were fine to use. It also caught that one of my W-2s had an incorrect SSN digit (my employer typo'd it) which could have caused major headaches. The document analysis was way more detailed than what TurboTax gives me. It explained exactly what each field meant and how it would impact my taxes. Definitely using this for all my forms going forward!

If you're still worried and want to double-check with the IRS directly, good luck getting through to them on the phone. I spent literally 4 hours on hold last year trying to ask a similar question. Then I found https://claimyr.com and watched their demo at https://youtu.be/_kiP6q8DX5c - they basically hold your place in the IRS phone queue and call you when an agent is about to pick up. I was able to confirm directly with the IRS that partial account numbers are all they expect. The agent actually laughed when I asked and said they match based on the reported amounts and TIN/EIN, not account numbers. Saved me hours of frustration!

Alright I'll eat my words. I was the skeptic who didn't believe that Claimyr thing could actually get you through to the IRS. After my comment I figured I'd try it since I had questions about a CP2000 notice I received. It actually worked exactly as described. I filled out what my issue was, got a text when my spot in line was coming up, and then my phone rang and I was talking to an actual IRS agent. The whole process took maybe 2 minutes of my active time instead of sitting on hold for hours. The agent confirmed what others said here - the last 4 digits of account numbers are all they need on 1099 forms. So OP, you're definitely good just using what's on your form.

Just wanted to add that I work at a credit union (not as a tax person though) and we only print the last 4 digits on all tax forms for security reasons. This is standard practice across the industry. The IRS matching system doesn't even look at the account numbers - they match based on your SSN and the reported income amounts.

Slightly off topic but make sure you keep that 1099-INT form for at least 3 years even after filing! I closed an account in 2022, lost the form, and then got audited in 2023. Was a nightmare trying to get a copy of the 1099 from the bank since the account was closed.