As Opus 17 and I explained, under the tax code there is a taxable difference. If the purported Roth conversion occurred first, the amount converted up to the amount of the RMD would constitute a failed conversion. Reporting that portion on your tax return as a completed conversion would mean that you were filing inaccurate tax return (only making it seem like there is no taxable difference). The RMDs for all of your traditional IRAs must be satisfied before doing Roth conversions of any other amounts from your traditional IRAs.
