You need to amend your 2016 tax return to report the $200 excess contribution made for 2016 and pay the 6%, $12 penalty. Unless you can apply this $200 as part of your traditional IRA contribution for 2017, the excess must again appear on your 2017 Form 5329, subject to another 6%, $12 penalty. If you can't apply it as part of your 2017 contribution, to avoid another 6% penalty for 2018, you'll need either be able to apply it as a 2018 contribution or obtain a regular distribution of $200 from your traditional IRA, taxable and subject to a 10% early distribution penalty. A return of contribution after the due date of your  tax return is not permitted to be nontaxable because your contribution in 2016 exceeded $5,500. If you made the maximum traditional IRA contribution for 2017, you can obtain a "return of contribution"(not a regular distribution) of $200 of that contribution, with the distribution being adjusted for any gain or loss, to make room to allow the $200 excess from 2016 to be applied as part of your 2017 contribution.
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