There is no reason to amend now rather then wait for the 2018 1099-R to arrive, then amend. Nothing is to be gained by amending now and if anything else is discovered that requires changing that would require amending the amended return.
The 1099-R should have a code JP in box 7, the returned excess amount in box 1 and the $18 earnings in box 2a which will be taxable income on line 15b on the 1040 form and also subject to a 10% ($1.80) early distribution penalty if you are under age 59 1/2 . This goes on your amended 2017 tax return. In the interview you select that it is a 2018 1099-R, not 2017.
And the 1099-R will be a 2018 1099-R received next January in 2019 (not 2018). Nothing goes on your 2018 tax return.
**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.**
