Code J indicates a regular distribution made from a Roth IRA before age 59½. If the amount of this distribution was equal to the amount of the excess contribution, it eliminates the penalty for this excess for 2017 and beyond and is tax and penalty free.
Despite being an excess contribution, the contribution for 2016 added contribution basis in your Roth IRAs. Since contribution basis comes out first, tax and penalty free, in addition to your 2017 code J distribution eliminating the excess on 2017 Form 5329 Part IV, the taxable amount calculated on 2017 Form 8606 Part III will be zero. Since only the taxable amount a code J distribution is subject to early-distribution penalty, there is also no penalty on this distribution.
