2026 IRS Limits for the Backdoor Roth
- •IRA contribution limit: $7,500 ($8,600 if 50+, including the $1,100 catch-up).
- •Roth IRA direct-contribution phase-out: $153,000–$168,000 (single/HoH) and $242,000–$252,000 (married filing jointly).
- •No income limit applies to either step of the backdoor — not the Traditional IRA contribution, not the conversion. Only direct Roth contributions are income-capped.
- •The IRS pro-rata rule (Form 8606) taxes a conversion based on ALL your Traditional, SEP, and SIMPLE IRA balances combined — not just the account you convert.
- •401(k) and 403(b) balances do not count toward the pro-rata calculation — only IRA-type accounts do.
The Real Problem This Solves
The backdoor Roth is simple in theory: contribute after-tax money to a Traditional IRA, then convert it to a Roth. High earners do this because direct Roth contributions phase out above a certain income. What most explainers skip is the pro-rata rule — if you have any other pre-tax IRA money sitting around, usually an old 401(k) you rolled into an IRA years ago and forgot about, the IRS taxes your "tax-free" conversion proportionally against your entire IRA balance.
People find this out after filing, when their accountant asks why they owe tax on a conversion they thought was already after-tax money. This calculator runs the actual Form 8606 math against your real account balances before you convert, so there are no surprises at tax time.
How the Pro-Rata Rule Actually Taxes You
The IRS looks at every Traditional, SEP, and SIMPLE IRA you own as one pool. Your nontaxable percentage is your total basis (after-tax contributions) divided by the total value of that pool — and that percentage applies to any conversion, no matter which specific account the money came from.
Example: Priya earns too much to contribute to a Roth directly, so she contributes $7,500 (nondeductible) to a new Traditional IRA and converts it a few days later, by which point it's grown to $7,510. She also has a $42,500 rollover IRA from a job she left years ago — all pre-tax. Her total IRA pool is $50,010, and only $7,500 of that is basis. Nontaxable percentage: 15.0%. So her $7,510 conversion is 85% taxable — about $6,384 of taxable income, roughly $1,532 in tax at a 24% bracket, even though she "already paid tax" on the $7,500 she put in.
Had she rolled that old $42,500 IRA into her current employer's 401(k) first — most plans accept this, and 401(k) balances are excluded from the pro-rata calculation — her taxable amount would have dropped to about $10.
| Scenario | Taxable Amount | Tax Owed (24% bracket) |
|---|---|---|
| $42,500 old rollover IRA left in place | $6,384 | $1,532 |
| Same $42,500 rolled into a 401(k) first | $10 | $2 |
Frequently Asked Questions
What is the pro-rata rule?
An IRS rule (calculated on Form 8606) that treats all your Traditional, SEP, and SIMPLE IRAs as one combined account for tax purposes. When you convert any amount to Roth, the taxable share is based on your total pre-tax balance across all those accounts — you can't choose to convert only the after-tax portion.
Does my 401(k) count toward the pro-rata calculation?
No. Only IRA-type accounts (Traditional, SEP, SIMPLE) count. 401(k), 403(b), and most other employer plans are excluded — which is exactly why rolling an old IRA into a current 401(k) before converting is the standard fix for the pro-rata trap.
Is there an income limit on the backdoor Roth itself?
No. There's no income limit on contributing to a Traditional IRA (nondeductibly) or on converting it to a Roth. The only income limit is on contributing to a Roth IRA directly — that gap is the entire reason the backdoor route exists.
Do I need to file anything with the IRS?
Yes — Form 8606 in any year you make a nondeductible Traditional IRA contribution and/or convert to Roth. It tracks your basis so you (and the IRS) know what's already been taxed. Skipping it is the most common backdoor Roth mistake and can cause you to be taxed twice on the same money.
Is the backdoor Roth legal?
Yes. It's a long-standing, widely used strategy that Congress explicitly acknowledged in the conference report accompanying the 2017 Tax Cuts and Jobs Act. There's no minimum waiting period required between the contribution and conversion steps, though many people wait a few days out of caution.
What if I can't roll my other IRA into a 401(k)?
Not every employer plan accepts incoming rollovers, and not everyone has a current employer plan. In that case you either accept the pro-rata tax hit on this conversion (a one-time cost, since your basis carries forward on future conversions) or, if you're self-employed, consider a Solo 401(k), which also accepts IRA rollovers and keeps them out of the pro-rata pool.