The $50 penalty is due for each tax year in which you’re required to file Form 8606 to report a nondeductible contribution to a traditional IRA, but fail to do so, unless you can show reasonable cause.
The IRS’ 2021 Instructions for Form 8606 aren’t clear that the penalty should be included, but you could most likely include them without worry. I’d suggest submitting a separate check for each tax year, writing “Form 8606 for Tax Year (enter the appropriate tax year)” in the memo portion of each check.
You’ll need to sign Form 8606, and send it to the IRS at the same place you would otherwise file Form 1040, 1040-SR, or 1040-NR. You can see that address in the Where Do You File? section on the last page of the 2021 Instruction 1040.
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