type the 1099-R EXACTLY as it's presented to you....not following what back pay ('arrears') has to do with an IRA / RMD..... (especially make sure the codes are correctly typed) and answer any questions TT asked. 

The 1099-R should show Code 4 in Box 7, this indicates that the distribution was due to death.  You should double check how you entered the information in TurboTax.   After you enter your Form 1099-R, be sure to walk through the follow-up Turbo tax questions so that the military retirement pay you received is reported properly on your return.  I am sorry for your loss.

...AND...and if he was age 70.5 or older in 2019, then the RMD question is always asked for any 1099-R form, even on a Retirement/Pension $$ in which you have no control over the RMD amounts.  When asked this for that Military 1099-R, you just answer YES...it was an RMD, and all of the RMD was received. 

(OK, I suspect there will be some with certain box 7 codes where the RMD question will not be asked...but you must use whatever box 7 codes are on your 1099-R)

Thank you for your kind reply.  I correctly entered the info but still treats the military arrear pay as an rmd.  I went to the other big online tax preparation service and I can enter the information with them correctly.  There program is set up so you have a spot to check off for arrears of a military pension on a deceased spouse which unfortunately TurboTax does not offer.  Once again thank you for your reply