Backdoor Roth IRA Calculator

Once your income passes the Roth IRA limits — $153,000 for single filers and $242,000 for married couples in 2026, phasing out completely at $168,000 and $252,000 — you can't contribute to a Roth IRA directly. The backdoor Roth is the standard workaround: contribute to a traditional IRA without taking a deduction, then convert it to a Roth. For many physicians, dentists, pharmacists and dual-income healthcare households, it's one of the simplest ways to add tax-free retirement savings.

What this calculator does

Enter your age, the age you'll start withdrawing, your yearly contribution, an expected return, the "tax drag" a regular brokerage account would have, any pre-tax IRA balances, and your marginal tax rate. It shows:

• what your Roth will be worth at withdrawal age, tax-free,
• what the same savings would be worth in a taxable account,
• the Roth advantage,
• any tax due on each conversion because of the pro-rata rule, and
• your total contributions.

The formula in plain English

Roth value is the future value of a monthly contribution (your yearly amount ÷ 12) growing at your expected return until withdrawal age. Qualified Roth withdrawals are tax-free.

Taxable account value uses the same contributions but a lower return — your expected return minus the tax drag from yearly taxes on dividends and capital gains. A 1% drag is a reasonable middle estimate.

Pro-rata rule. The IRS treats all your traditional, SEP and SIMPLE IRAs as one pot. When you convert, the taxable share is:

pre-tax IRA balances ÷ (pre-tax balances + your new non-deductible contribution)

measured on December 31 of the year of the conversion. That share of the conversion is taxed at your marginal rate.

A worked example

Dr. Nguyen is 35, plans to start withdrawals at 62, and contributes the 2026 limit of $7,500 each year. She expects a 7% return.

• After 27 years, her Roth would be worth about $598,000, all tax-free.
• The same savings in a taxable account, with a 1% tax drag, would be worth about $504,000.
• The Roth advantage is about $94,000 — before counting the taxes she'd still owe on gains in the taxable account when she sells.
• She has no pre-tax IRA money, so her conversions are essentially tax-free.

Now suppose she has $30,000 in an old SEP IRA from moonlighting. Then 80% of each conversion is taxable, and at a 37% marginal rate she'd owe about $2,220 each year. Rolling that SEP into her hospital's 403(b) before December 31 would remove the problem.

Why it matters at each career stage

If you're: Resident / fellow

Your income is probably below the Roth limits, so contribute directly — no backdoor needed. Your tax rate is as low as it will ever be, which makes Roth money especially valuable.

If you're: Employed

Make the backdoor Roth an annual habit, ideally in January. Check for any pre-tax IRA money first, and keep good records for Form 8606. If both you and your spouse do it, you can shelter $15,000 a year.

If you're: Practice owner

Owners often have SEP IRAs, which trigger the pro-rata rule. Switching to a solo 401(k) or a practice 401(k) keeps that money out of IRAs and keeps the backdoor clean.

Step by step

1. Make sure you have no pre-tax IRA balances, or roll them into an employer plan.
2. Contribute to a traditional IRA and don't deduct it.
3. Convert the balance to your Roth IRA once the money arrives.
4. Invest it inside the Roth.
5. File Form 8606 with your tax return.

Where does a backdoor Roth fit with everything else? Most people capture their employer match first, then fund the backdoor Roth, then save more in their workplace plan. See your workplace plan's growth with the 403(b) calculator, check your target with the FI number calculator, and read the full backdoor Roth walkthrough.