It would be easier but it is not how it is done ... the W-2c didn't change box 1 so you can't just do so. You must only amend the 2015 return for the W-2 changes and then do the "right of claim" on the 2017 return. Good news ... since you must be using the downloaded version to amend the 2015 return you can make a "test" copy of the return and use the copy to make the box 1 correction and see the tax difference to use on the 2017 return.
If you want to play around
with different figures and tax scenarios without affecting your original return
you can
>>>In the TurboTax CD/Download software by creating a test copy:
1. Open your return
in TurboTax.
2. From the File
menu, choose Save As.
3. Give the copy a
new name to distinguish it from the original (for example, by adding
"Test" or "Example" to the file name).
4. Click Save.
You are now safely working in the test copy and anything you do here will not
affect the original.
https://ttlc.intuit.com/questions/1900642-how-to-make-a-test-copy-of-your-return
Turbotax on-line does
not support the "claim of right" computation. Turbotax desktop,
in the forms mode, permits the credit to be entered in the "smart worksheet"
above line 72, but you still would need to compute it manually.
