Roth IRA Conversion: When Does Paying Tax Now Make Sense?
A Roth IRA conversion involves moving pre-tax money from a Traditional IRA to a Roth IRA, paying income tax on the converted amount today in exchange for tax-free growth and withdrawals forever. It's one of the most debated topics in personal finance — and for good reason. The decision hinges on a single variable you can't know for sure: whether your tax rate will be higher or lower in the future.
The Math
The break-even is simple: if your future marginal tax rate is the same as your current rate, conversion is a wash — mathematically identical whether you convert or not. If your future rate is higher, converting saves you money. If it's lower, you're better off not converting. The problem? Nobody knows their tax rate 20 years from now.
When Conversion Makes Sense
- Low-income years: If you're between jobs, on sabbatical, or retired early before RMDs kick in, your marginal rate may be temporarily low — a perfect conversion window.
- Young investors: Early in your career, before your income ramps up, converting a small Traditional IRA can be cheap.
- High future tax rate expected: If you believe tax rates will rise across the board (historically a good bet), locking in today's rates makes sense.
- Backdoor Roth complications: If you have a large Traditional IRA balance that blocks the backdoor Roth strategy, conversion clears the way.
When It's Overrated
The personal finance industry loves Roth conversions because they feel good — "pay taxes now to never pay them again!" But the math is often underwhelming. If you're in your peak earning years and converting at 32%+, you need a massive future rate increase to come out ahead. And paying the conversion tax from the IRA itself (rather than from outside cash) reduces the amount that compounds, further eroding the benefit.
The RMD Angle
One genuine advantage: Roth IRAs have no Required Minimum Distributions (RMDs). If you have a large Traditional IRA, RMDs can push you into higher tax brackets in retirement and increase Medicare premiums (IRMAA). Converting some of your Traditional IRA to Roth can reduce future RMDs — a benefit this simple calculator doesn't fully capture.
2026 Roth IRA Limits at a Glance
The numbers changed for 2026, and they matter for every conversion decision. The IRA contribution limit rose to $7,500 (from $7,000 in 2025), with $8,600 allowed if you are 50 or older. Direct Roth contributions phase out between $153,000 and $168,000 of modified AGI for single filers and between $242,000 and $252,000 for married couples filing jointly — above those ranges you must use the backdoor strategy. Traditional IRA conversions have no income limit and no dollar cap, which is why the calculator above can model a conversion of any size. Note that a conversion is not a contribution: it never counts against the $7,500 limit.
The Five-Year Rule in Practice
Many conversion mistakes trace back to the five-year rule, so it is worth stating clearly. Contributions to a Roth IRA can be withdrawn any time, tax- and penalty-free. Converted amounts are also penalty-free after the later of (a) five years from the start of the year of conversion or (b) age 59½ — so a conversion done at age 40 is fully accessible at 45 for the principal, with earnings accessible at 59½. If you convert in a year when you are under 59½, plan to wait five years before touching the converted money. The calculator's recommendation assumes you can wait; if you cannot, the conversion may not be right for you.
Common Mistakes People Make
- Paying the conversion tax from the IRA itself. Withholding tax from the converted amount reduces what compounds tax-free — pay the tax from cash instead.
- Ignoring the pro-rata rule. Pre-tax IRA balances make every conversion partially taxable; roll them into a 401k first if you use the backdoor.
- Converting in peak earning years. A 32% conversion today needs a very high future rate to pay off; prefer low-income years.
- Forgetting state taxes. Some states tax conversions even when the federal bill is zero — check before you convert.
- Not filing Form 8606. Non-deductible contributions and conversions must be reported or the IRS treats the whole balance as taxable.
Action Steps
- Estimate your current and future marginal tax rates before converting anything.
- Run the calculator above with your real balance, rate, and time horizon.
- If converting, pay the tax from outside cash and keep the full balance compounding.
- Track your five-year clocks per conversion and file Form 8606 every year.