While the question requires some guessing, the adviser says, “We’re probably seeing lower tax rates now relative to what we’ll probably see in the future,” given the Obama Administration’s plans to stimulate the economy.

Currently, of course, the nation is anticipating a round of tax cuts, particularly for the middle class, but “I think what we’re doing is kicking the can down the road and postponing the pain, so we’ll be paying higher taxes when we can handle it,” Rustman says.

Reducing taxes now or later? Essentially, Rustman says, “You can pay taxes now or not pay and guess later, during retirement." Those 401(k) participants who decide to "take the hit now," paying taxable dollars into their Roth 401(k)s and treating plan balances with tax-free growth during their working years and in retirement may sleep better at night, he believes.

On the other hand, there are clearly people who will be interested in reducing their tax rate now, when the economy is suffering, layoffs are rampant and credit is scarce. Someone making $150,000 a year putting a large portion of their salary into a traditional 401(k)—the maximum permitted level this year is $16,500 or $22,000 for those 50 and up—could ratchet down their tax bracket rather significantly, for instance.

“These are very personal questions,” Rustman explains. What’s important is to understand what the options are and how they pertain to your own situation.

If you’re still confused about what to do, free Roth 401(k) calculators can be easily found on the Web. For starters, check out AARP and Research401k.com.