If I buy turbo tax deluxe plus state from a store, can I add a second state. and if so, how much will it cost?

[SteamTrain]

Yes, you can buy additional states from within the program, as long as you have a US credit or debit card with a US billing address.

You have to start a 2017 tax file before you buy any state

Start your Federal entries first.  then work on your Free state and select it as your free one when you start it.

.....then, after that, when you start on the second state, you will be asked to pay $40 (ok..39.99 for the nit-pickers).

(Maine isn't available yet)

[mesquitebean]

The price for the second state normally increases around mid-March to 44.99, but exactly when is unpredictable.  TurboTax reserves the right to raise prices at any time.  But if you buy the second state in the next few weeks, it should be at the discounted price of 39.99.

When you buy your Deluxe in a store, read the box carefully, since Deluxe comes in 2 versions--one that is Federal-only, and one that is combo Federal and State.