Do I still need to enter my spouse's name, info., etc. since we have not filed a joint return in over 20 years, and he passed away in March 2018?

[peach-11]

My husband and I had been separated for 20 years before he died in March 2018.  During that time we never filed a joint return.  I filed as single.

[KatrinaB]

You are considered married for the entire year, even though your spouse died during 2018. Therefore, you need to enter his information on your married filing separate return.