First, here are some common situations where you don't have to file a second state return:
- Interest from an out-of-state bank or account. No need to file a return in that state; just report it on your federal return as you would for in-state interest.
- Out-of-state employer. Don't file a return in your employer's state unless their payroll department accidentally withheld taxes for their state instead of your resident or work state. More info
- Alaska, Florida, New Hampshire, Nevada, South Dakota, Tennessee, Texas, Washington, Wyoming. These 7 states don't collect personal income tax. However, if you earned money in one of these states but live in a state that does collect income tax, you are required to report the income on your resident state return. More info
- State reciprocal agreements. You won't have to file 2 state returns if your resident and work states have a reciprocal agreement and you submitted the proper exemption form to payroll. This article has info about both.
Now that those are out of the way, read on for situations where you probably have to file multiple state returns.