I'm NOT advocating for this but . . . what if you stick in $1 of bogus withholding and request a dirdep refund?
I remember the last time we had one of these things (or the time before?), the IRS instructed us to put in $1 of interest income so the returns could be efiled.
There are rumors (okay, tweets) that the IRS is going to make a website. I have serious reservations about how that will work, particularly for a non-filer SS recipient. Generally the IRS authenticates you with prior year AGI, etc. so . . . $0? Or they'll use some financial history from Equifax--oh wait maybe that's not such a good idea either . . .