Is there a penalty when amending 2021 tax return results in additional tax due?

[kckoo84]

I’m amending 2021 tax return due to missing 8606 form.

It results an extra income tax (due to pro-rata) so I owe the extra tax to Federal and state(CA).

In this case, is it just to send 1040x,1040,8606 and the amount I owe in 1040x(line20) for the federal and Schedule X (line 7)?

I’m wondering if there is extra penalty since the owed tax supposed to be paid till 04/15/2022 and now it is March, 2024

[Mike9241 · Accepted solution]

The payment is late, so yes the IRS and CA can charge penalties and interest.  The tax program will not compute these, so your choice is to pay what's indicated and let the tax authorities bill you or you can include something extra but all that will do is lower the interest portion of the penalty.

If you have a reasonable cause (that's a determination made by the tax authorities based on what you submit in writing as the reason for omission from the original return and also being 2 years late in amending) then the penalties can be abated but not the interest.