The passage of the Tax Cuts and Jobs Act late last year had a marked impact on Roth IRAs: to wit, taxpayers who wish to convert a pretax traditional IRA into a post-tax Roth IRA can no longer “re-characterize” (that is, reverse) the conversion for 2018 and later years.
The IRS recently clarified in FAQs on its website that, if you converted a traditional IRA into a Roth account in 2017, you can still reverse the conversion as long as it’s done by October 15, 2018. (This deadline applies regardless of whether you extend the deadline for filing your 2017 federal income tax return to October 15.)
Also, re-characterization is still an option for other types of contributions. For example, you can still make a contribution to a Roth IRA and subsequently re-characterize it as a contribution to a traditional IRA (before the applicable deadline).
