I have a foreign friend with US green card. He lived oversea the whole year in 2021.
He has some investments in US and got a bunch of 1099-INTs, 1099-DIVs, 1099-Bs. He said payers' addresses on these forms were in California, New York, Missouri.
(1) Does it mean he had income from 3 states' sources and had to file all these 3 state tax returns, even if he lived abroad the whole year?
(2) Does the payer's address state on these forms decide where the income should be allocate?
