Just about every article I've read on Roth IRA conversions discusses their benefits for people who might be in a high tax bracket once they retire.
What these articles invariably fail to mention is the negative impact that state income taxes could have and why, depending on where you plan to live, a Roth conversion might actually not be the best decision for everyone.
When you convert a 401(k) plan account or traditional IRA to a Roth IRA, you're making the conscious decision to pay income taxes today for the promise of a tax-free income tomorrow. This can be a wise choice if you are fairly confident that a) you'll be in a higher tax bracket during retirement, and b) Congress won't dramatically change the tax rules on Roth IRA withdrawals.
(Read more: Have you reviewed your 401(k) lately?)
Those with high incomes who are saving and investing successfully—and who believe they'll continue to have a high income once they retire—seem prone to a certain line of reasoning: Because the promise of tax-free income from a Roth IRA is so appealing, why not just take some retirement savings today, pay the tax at current levels and then sit back and enjoy tax-free income during retirement? After all, just about "everyone" thinks that taxes will be higher in the future, right?