You are correct. There is no 12a on Form 1099-R. It is most likely a type-o.
Generally, the program carries the information to your state for you. Box 14 is the state distribution. If box 12 is blank, do nothing. If you have a box 12 amount, you can fill in the taxable state amount for box 14. Be sure you have a state ID for box 13, and box 12 should be unchecked.
Please delete the form and re-enter the information paying careful attention to the box entries in TurboTax. The simplest remedy is often to delete and re-enter.
Hold on now...
Yes....12a is a typo...but the typo is that it is supposed to say 14 (the "a" is just the first State line on the 1099-R form as there can be two state lines)
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For 2020, what were boxes 12,13,14 on the 2019 1099-R....the IRS has renumbered them as boxes 14,15,16 for the 2020 1099-R form. So the error was "supposed" to indicate box 14 (not 12) , This text error in the error has been ongoing for weeks now, with no fix by TTX. But it is just a text error-in-the-error notice.
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For NY residents who get a 1099-R, the usual complaint in the software is that state withholding (box 14) is greater than the NY distribution amount (box 16) . The solution is to enter box 2a $$ value into box 16.....or if box 2a is empty, then the Federally-taxable amount of box 1 is used (but that's usually just box 1)
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i.e in the software 1099-R form for 2020
Box 14 is State Withholding.....the two-part box 15 is the State designation and state ID number....and box 16 is the state distribution amount (usually empty on paper 1099-R forms, but needs a real number for many states...as I said, usually box 2a)