How do you add the state of Washington to file my taxes?

WA has no state income tax.

The best way to add a state is to get back into your return- do this only if you have not filed the return. 

1. Sign into your Turbo Tax account

2. Click on tax home or take me to my return

3. Scroll down till you see Your tax returns and documents

4. Click on your 2018 return, and then select add a state