My husband's father passed away in October 2019. His father had been living in his deceased wife's home since her passing in 2009. The home was in her children's name, my husband's step-sister and step-brother. When the home sold in September 2020, the step-siblings wanted to share the proceeds with my husband. During the closing process, my husband did not receive a 1099 since he was not listed as a seller. My question is how do we report those proceeds we received from the sale of the home?
Since your husband didn't have any vested financial interest in the home he wouldn't receive a 1099 for the home sale. The money received from his step siblings is considered a gift. Gift treatment is a bit different. The person(s) who gave the gift files the gift tax return, if necessary, and pays any tax. Essentially, gifts are neither taxable nor deductible on your tax return. The annual exclusion for gifts is $15,000 for 2020.
Here's a great article on The Gift Tax https://turbotax.intuit.com/tax-tips/estates/the-gift-tax/L1sFpFeXV