@BBDTx2
Use Form 1040-X to change or add information on an already filed tax return.
The Form should have been attached to your original Form 1040.
It's been posted here that IRS has been sending back standalone forms and asking for 1040-X.
It costs you nothing to report the missing 8606 on 1040-X.
If you aren’t changing any dollar amounts you originally reported, you don't have to do column A B C.
You aren't changing any dependents.
Just fill out the top and Explanation Part III
The blank form in fillable PDF format and its instructions are available at www.irs.gov.
For several years back anyway.
you would need 1040-X for each year.
The policy of IRS to apply the penalty, I can't comment.
I've never seen any post here that the IRS charged the $50.
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I've always argued to put the missing total prior years basis on the current year form 8606 and
send in one form and be done with it.
I get a lot of pushback here on that suggestion.
Use your own judgement.
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From 2017 IRS Pub 590A
"Failure to report nondeductible contributions. If you
don’t report nondeductible contributions, all of the contributions
to your traditional IRA will be treated like deductible
contributions when withdrawn. All distributions from
your IRA will be taxed unless you can show, with satisfactory
evidence, that nondeductible contributions were made. [my italics added]"
