If I received a distribution from a retirement plan after 2016, how do I know what amount to put in the "After 2016 to 2017..." box? Do I use total gross or taxable?

[alethiadahlin]

This is in the "Tell us about your distributions from retirement plans" sections under Deductions & Credits.

[dmertz]

Total gross (assuming that you did not roll any over).  The fact that some or all of the regular distribution is not taxable doesn't matter.  Congress didn't want you to get a tax credit for just taking money out and putting it back.