The tax laws change every year. Federal filing for the tax year 2019
(deadline in 2020 is July 15th, extended due to Covid-19) was $12,200
for a single person. It was $12,000 ($200 less) for tax year 2018. Tax
year 2017 was $10,400. If your income didn't hit those marks you were
*not* required to file a Federal tax return.
State tax (yes, Missouri has a state income tax) but he only has to file
if he was required to file a Federal return. Many other factors include
interest income from bank accounts/investments and of course his rental
income. They know that info from the "occupancy permits" he was
surprised he had to get.
It seems apparent (to me) at some point he did need to file a Federal
and State return and he simply ignored it. Busy playing his djembe or
sipping a Cuppa Plus. Now he's having to play catch-up. He's very
lucky he didn't have to pay compounded interest dating back to 2017 or
2016... let it go long enough and they could take that house of his.
Jill