1099R

My husband passed away at 64 in 2016. I have been receiving his General Motors pension since then. I get a monthly income from his pension. I also receive a 1099 R. This year they asked his year of birth and when I enter it. The program is telling me I need to calculate an RMAD. This is not an inherent IRA. It is a pension received monthly. Please advise. This has never happened before

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