Passed by both the House and Senate, right before the Christmas holiday President Trump signed into law the “Tax Cuts and Jobs Act” that, among other things, eliminates Roth IRA recharacterizations beginning January 1, 2018.
Until now, the rule was you had an opportunity to recharacterize your Roth IRA contribution if you recharacterized by the deadline. This gave IRA owners a little bit of flexibility should an unexpected change in their IRA planning occur or they simply changed their mind.
So anyone planning to recharacterize their Roth IRA contribution or conversion must do it by the end of 2017.
Source: Tax Cuts and Jobs Act