Ok, thank you for letting me know that severance income had employer's resident state taxes withheld.
Then right now you would have to file a non-resident return reporting this income (and taking credit for State taxes withheld).
Then you would file a resident return reporting all the income and taking a credit for taxes paid to then non-resident state (as long as your resident state has state income taxes).
The other option is to: Talk to employer asap and tell them to correct this so only taxes are withheld from the resident state where you reside due to primarily doing work from home.
