I received a stimulus check today for my deceased father (d. Jan. 2018). On the outside of the envelope near the preprinted first class postage is a box with the words  [  ] "IF RECIPIENT DECEASED Check here and drop in mailbox".

IF you don't have the envelope, the return address is:

U.S. Department of the Treasury

Bureau of the Fiscal Service

P.O. BOX 51320

Philadelphia,  Pennsylvania  [social security number removed]