Personally, if the RMD is the only income for 2020 (Zero Income), but your 1041 client will have sufficient income to have to file in future years, I would file a Zero Income/Loss Tax Return with the IRS for 2020 anyway. It leaves no room for IRS sending your client a late filing notice (even with zero income). As well, your client/you/IRS will have a sequential record of all years tax returns.