To figure out income subject to tax by another state, start by determining your residency status, as this affects how your income is taxed. Check the specific tax rules of each state, including any reciprocal agreements to avoid double taxation. Use apportionment schedules to divide your income between states based on where it was earned.
You may need to file tax returns in each state where you earned income. To avoid double taxation, claim a credit on your resident state return for taxes paid to another state.
Part-year residents pay tax on all income received while residing in the state, while nonresidents pay tax on income earned from work in the state and other sources within the state. Use an apportionment schedule to assign the right share of your income and deductions to each state.
If using TurboTax it'll ask you questions in the "My Info" section to help you determine the states you need to file in then help you prepare your return.
For more detailed help, you can refer to TurboTax Help Articles,