A Roth conversion could cost you more in 2013. That's because of several new and/or increased taxes in play for this year. The top income tax bracket is 39.6% for individuals married filing jointly with taxable income in excess of $450,000. A large Roth conversion could easily push an individual into the highest income tax bracket. When adjusted gross income for our married couple exceeds $300,000, personal exemptions and itemized deductions begin to phase out. And, when modified adjusted gross income exceeds $250,000, net investment income for our married couple becomes subject to the 3.8% surtax. So you can see how a Roth conversion could cost an individual more in taxes this year.