1099R

Box 13 is for the Date of Payment.  To get the Maryland deduction for military retirement, after you enter the 1099-R information look for the screen below. TurboTax will use this information when you complete the Maryland tax return.

@jimeagen 

You Might be referring to box 13 on last year's 1099-R form, where you could enter "MD" for the state.   The 1099-R form was redesigned for 2020, and  that was moved to  box 15 on the new 2020 form.

1) make sure you are using a 2020 form 1099-R

2) I can't know if the printers messed up the DFAS form for 2020 and didn't get those new boxes properly programmed in.  Some of the early DFAS 1099-R forms already had to be reissued once this year for a missing digit on the FEIN.