Hal_Al
Level 15

Deductions & credits

You have until 4-15-19 to amend a 2015 return (unless you filed an extension back then which gives you to 10-15-19).
The mechanics of amending is beyond my expertise. You may have to start a new thread to get help.  I usually just refer people to this FAQ
 <a rel="nofollow" target="_blank" href="https://ttlc.intuit.com/questions/1894381-how-to-amend-change-or-correct-a-return-you-already-filed"...>