Even though Washington doesn’t have a state income tax (so there’s no state return to file), if you earned income in other states, they may require you to file a return.
If you’ve already filed your return in one of those states, go to the state list to find that state’s refund tracker.
If you haven’t filed a return in the other states, here’s what you need to be aware of:
If you’re on salary, you’ll have to file a nonresident return for the state you work in, unless it has a reciprocal agreement with your state. Since you’re likely paying withholding to the state you work in, filing a return means you may get a refund (although you might owe money).
If you’re receiving 1099-MISCs, you pay taxes to the state where your home office is located. Depending on a variety of factors, including whether you paid estimated taxes, you might get a refund or you might owe money.
If you have rental property or investment property in another state, you pay taxes to the state of your primary residence—however, there can be complex rules, so check with the Departments of Revenue in both states to be certain you’re in compliance.
If you spend more than a certain number of days in some states, you're considered a resident. The rules aren't consistent from state to state, so if you have any concerns, check with each state for the specific residency rules that apply to your particular situation. There are also rules that vary from state to state about the minimum amount you must report.