The code J says it is a Roth, the code P says it is a 2017 contribution returned in 2018. If a loss then box 2a should be zero - you cannot deduct a Roth IRA loss.
It makes no sense at all to ever have withholding on a return of contributions that are not taxable or were returned in the tax year after the year of contribution because the box 4 tax withholding can only be applied to the year in which it was withheld. For a code P that means that even if the 2017 contribution *was* taxable, the withholding could not be used in 2017 but would be have to be applied to 2018 tax.
A code 8J on the other hand that had taxable earnings might have withholding to pay the tax on the earnings because a code 8 means that it was returned in the same year as the contribution was made.
**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.**
