Is there a penalty/interest for filing after October 15 if a refund is owed to me?

[calaguna]

I have overpaid my 2024 quarterly Estimated Taxes and will be due a refund or credit for 2025 taxes.  Is there any penalty or interest due if I am unable to complete the return by October 15, 2025? For example: if I don't file the return until November 1, 2025 and the return shows I am owed a refund, is there any late filing penalty or interest assessed? Is this true at the state level too (California)?

[xmasbaby0]

There is no penalty if you are getting refund; if you are getting a refund you have three years to file and still receive the refund without penalty.   But e-filing will close permanently for 2024 returns after October 15, so if you miss that deadline, you will need to file by mail.

[AmeliesUncle]

While there would not be a penalty or interest if all of the tax was paid by April 15th, that doesn't necessarily mean filing late won't be problematic.  For example, some elections on the tax return are required to be on a timely filed tax return.  If your tax return has any of those elections, filing late would mean you can't make those elections.