Retirement tax questions

@dps098 - Probably not - depending...

If this was a return of an excess deferral on a employer sponsored retirement plan (only code P in box 7) then the box 2a amount would increase you line 7 wages by that amount.

If a return of excess Roth contribution from a IRA then box 7 would have a code JP and the box 2a earnings would go on line 15b.   

That might or might not affect other credits or capital gains carry overs to 2016.   If it does not change any 2015 to 2016 carryover amounts then there would be no need to restart 2016.
**Disclaimer: This post is for discussion purposes only and is NOT tax advice. The author takes no responsibility for the accuracy of any information in this post.**