Traditional IRAs are tax-deferred accounts, which means that neither deductible contributions nor earnings are taxed until withdrawals begin. Federal income tax is paid on the proceeds when they are withdrawn.

Comparison
The concept sounds good, however, are these online calculators accurate? Different assumptions are made with different calculators and some even compute different answers. The biggest assumption is that the user or typical IRA account holder is going to understand and be savvy on the terms and definitions used in the calculators.

Definitions also read differently on different sites. Some sites, including Aim Funds, www.aimfunds.com/roth/rothroll.asp, ask what the total value of the nondeductible IRA contributions are, while others, such as Aetna, www5.aetna.com/rothIRA/RothIRA.asp, ask for the percentage of traditional IRA contributions that are after-tax. Both basically mean the same thing.

The different online calculators even ask a series of different questions. To be eligible for a rollover the holder cannot file her taxes as "Married, filing separately." Aetna and some other online calculators I used did not ask that question. If the question is not asked, the calculator has to assume the holder and her spouse do not file their tax returns separately. Also, most of the calculators asked for the adjusted gross income while the calculator on the Invesco, www.invesco.com/, site asked for the annual household incomes of the holder and his spouse. The adjusted gross income and household income can be (and usually are) two different amounts.

Conclusion
Users need to go to the online calculator prepared. They need to know their current federal tax rate, and also anticipate what their tax rate will be when they retire. They also need to know their annual adjusted gross income, total current balance of their IRA accounts and total nondeductible IRA contributions for a start.

Anyone serious about converting to a Roth IRA or who wants to know his options, it would be in his best interest to talk to someone versed in the new law. One should contact her investment broker and leave the online calculators to what they are intended for, educational or illustrative purposes.