I Forgot to File Form 8606 in 2020 – Should I File It Now?

[webster2004]

Hi Experts,

I’d appreciate your help with my situation:

• In 2019, I opened my first Traditional IRA and made a nondeductible $6,000 contribution (reported on Form 8606 via TurboTax, establishing my IRA basis at $6,000).
• In 2020, I converted the full $6,000 to a Roth IRA (a backdoor Roth conversion) but forgot to file Form 8606 for 2020 to report the conversion.
• From 2020 to 2024, I made no additional nondeductible IRA contributions, so my IRA basis in IRS records likely still shows $6,000, whereas I believe it should be $0 after the conversion

Since it's now 2025 and I can no longer amend my 2020 tax return, can I still file a standalone Form 8606 for 2020 to document my after-tax basis and Roth conversion? Would the IRS accept it, and is there any penalty for late filing? 

Thank you for your guidance!

Best,

[MinhT1]

Yes.

You can fill out and file this form 8606 for 2020 now as a standalone form. You do not need to amend your 2020 tax return. You can send this form to the IRS at the address where you would file your tax return. This depends on your state of residence.

Please find the address in this IRS document.

There is a $50 penalty for filing the 8606 late unless you can show reasonable cause.

[webster2004]

Thank you @MinhT1 , I will file Form8606 for 2020.

Just out of curiosity, what happens if I don’t file Form 8606 for 2020?

Without filing Form 8606 for 2020, my IRA basis will remain $6,000. I won’t lose anything although the IRA basis is incorrect, right? Unless the IRS imposes a penalty on me after I retire.