Roth vs. Traditional IRA Calculator

Tax Timing Is The Core Tradeoff

The fundamental difference between a Roth and a Traditional IRA lies in when you pay taxes. With a Roth IRA, you contribute after-tax dollars; your contributions are not tax-deductible today, but your investments grow tax-free, and your withdrawals in retirement are completely tax-free. Traditional IRAs reverse this timeline: your contributions are made with pre-tax dollars (which can reduce your taxable income today), but the investments grow tax-deferred, and your withdrawals in retirement are taxed as ordinary income.

Choosing the right account requires comparing your current marginal tax rate with your expected tax rate in retirement. If you are in a high tax bracket today and expect to be in a lower bracket in retirement, the immediate tax deduction of a Traditional IRA is typically more valuable. If you are in a low bracket today and expect your retirement bracket to be higher, paying taxes now with a Roth IRA is usually the better choice.

Invested Tax Savings Comparison

To make this comparison fair, the calculator does not simply compare the final balances. Traditional IRA contributions lower your tax bill today, freeing up cash that can be invested elsewhere. The calculator assumes you take this current-year tax savings and invest it in a taxable brokerage account, letting it compound at the same rate over your savings horizon.

Consider a worked example using the calculator's default values: a $7,000 annual contribution over 25 years at a 7% average annual return, comparing a 24% current tax rate against a 22% retirement tax rate. Under both plans, the pre-tax principal grows to a headline figure of $442,743. In the Roth IRA, this full $442,743 is yours to keep tax-free. In the Traditional IRA, the balance is subject to a 22% tax on withdrawal, leaving you with $345,340 after-tax.

However, the Traditional IRA saves you $1,680 in taxes annually (24% of $7,000). Compounding these tax savings at 7% over 25 years generates an additional $106,258 after-tax. Adding this to the traditional balance yields a total Traditional strategy value of $451,598 ($345,340 + $106,258). Because your current tax rate (24%) is higher than your retirement tax rate (22%), the Traditional strategy wins by a net advantage of $8,855.

Eligibility And Deduction Rules

Both accounts have strict IRS rules governing contributions, deductions, and withdrawals. While anyone with earned income can contribute to a Traditional IRA, the ability to deduct those contributions from your taxes is phased out at higher income levels if you or your spouse are covered by an employer retirement plan like a 401(k).

Roth IRAs have strict income limits that restrict high earners from making direct contributions. To bypass these limits, some high-income savers use backdoor Roth strategies. A backdoor Roth IRA is a strategy for high earners whose income exceeds the direct contribution limits, allowing them to make a non-deductible contribution to a Traditional IRA and then quickly convert it to a Roth IRA.

However, you must navigate the IRS pro-rata rules during a conversion. Under the IRS pro-rata rule, when converting Traditional IRA funds to a Roth, the tax is calculated based on the ratio of all your pre-tax and after-tax IRA assets combined, meaning you cannot convert only the non-deductible portion tax-free if you have existing pre-tax IRA balances elsewhere.

Retirement Planning Mistakes To Avoid

The most common mistake when choosing a Traditional IRA is failing to invest the current-year tax savings. If you spend the tax refund or cash-flow savings rather than investing it, you lose the compounding power that offsets the future retirement tax bill, making the Roth IRA mathematically superior in almost all cases.

Another mistake is ignoring state income taxes. Your current and retirement tax rates should reflect both federal and state tax rates combined. If you plan to move from a high-tax state (like California or New York) to a tax-free state (like Florida or Texas) in retirement, a Traditional IRA becomes significantly more attractive.

Finally, do not forget about Required Minimum Distributions (RMDs). Traditional IRAs require you to start taking withdrawals and paying taxes at a certain age, whereas Roth IRAs have no RMDs during your lifetime, allowing the money to compound indefinitely or pass to heirs tax-free.

Scenarios Worth Testing For Your IRA

Start by running a 'same-bracket' scenario where your current and retirement tax rates are equal (e.g. 22% and 22%). You will find that both accounts yield the exact same after-tax value, illustrating that when rates are flat, tax timing is mathematically neutral.

Next, run a 'career-growth' scenario. If you are early in your career and in the 12% bracket today but expect to retire in the 22% or 24% bracket, model this change to see the substantial after-tax advantage of locking in the lower Roth tax rate today.

Finally, run a scenario where your retirement tax rate is much lower. Many retirees find that without a working salary, their taxable income drops significantly, making a pre-tax Traditional contribution today highly beneficial.

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