Yes, you can add the 3rd state on your return. If you lived in multiple states and earned income from each state in 2017. Normally, you would file part-year return for each state. Depending on the state you were living, some states does not require a state tax return.

Here are the steps to add an additional state on your return.

1. Start from Tax Home page of your TurboTax online
2. Click on Take me to my return
3. Click on the left side State tab
4. Click on Continue
5. At the bottom left, click on Add Another State (see attached screenshot page file)