The rules allow taxpayers to reverse their conversions until Oct. 15, either with an extension or an amended return.

WSJ: Tax Report: The Case for Filing Late

Mr. Slott says he plans to monitor his Roths and then reverse the conversions (called "recharacterization") of accounts that have dropped in value or lagged behind.

WSJ: Tax Report: How the Experts Are Handling Their Own Roth IRA Conversions