The backdoor Roth IRA is a workaround used by some high-income taxpayers who cannot contribute directly to a Roth IRA. The strategy can be useful, but the internet often makes it sound cleaner than it really is.
The basic version is:
- Make a nondeductible contribution to a traditional IRA.
- Convert the traditional IRA balance to a Roth IRA.
- Report the contribution and conversion on Form 8606.
For 2026, the IRA contribution limit is $7,500, or $8,600 if you are age 50 or older. The direct Roth IRA income phaseout starts at $153,000 for single filers and $242,000 for married filing jointly. See 2026 Roth IRA Income Limits for the full table.
Why the Backdoor Roth Exists
High earners may be blocked from direct Roth IRA contributions, but there is no income limit on making a traditional IRA contribution. There is also no income limit on Roth conversions.
That creates the opening. A taxpayer can make a nondeductible traditional IRA contribution and then convert it.
The tax result is best when the traditional IRA contribution has little or no investment gain before conversion and the taxpayer has no other pretax IRA balances.
The Pro-Rata Rule
The pro-rata rule is the main trap. You cannot choose to convert only the after-tax dollars in your traditional IRA if you also have pretax IRA money.
For tax purposes, the IRS looks across your traditional IRAs, SEP IRAs, and SIMPLE IRAs as one combined pool. The taxable and nontaxable portions of a Roth conversion are based on the ratio of after-tax basis to total IRA balance.
Employer plans such as 401(k)s are generally not included in this IRA pro-rata calculation.
Example 1: Clean Backdoor Roth
Alex is over the Roth IRA income limit and has no traditional, SEP, or SIMPLE IRA balance. In 2026, Alex contributes $7,500 to a traditional IRA and does not deduct it. A week later, Alex converts the $7,500 to a Roth IRA.
If there was no investment gain, the conversion is generally not meaningfully taxable because Alex already paid tax on the contribution. Alex still needs to file Form 8606 to show the nondeductible contribution and Roth conversion.
Example 2: Existing Pretax IRA Balance
Morgan has $92,500 in a rollover IRA from an old 401(k). Morgan makes a $7,500 nondeductible IRA contribution in 2026, bringing total IRA balances to $100,000. Morgan then converts $7,500 to a Roth IRA.
Only 7.5% of Morgan’s IRA pool is after-tax basis. That means only about 7.5% of the conversion is nontaxable. The rest is taxable, even though Morgan intended to convert the new nondeductible contribution.
This is the classic pro-rata surprise.
Example 3: Rolling Pretax IRA Money Into a 401(k)
Some taxpayers solve the pro-rata problem by rolling pretax IRA money into a current employer’s 401(k), if the plan accepts inbound rollovers. If the rollover is completed before year-end and no pretax IRA money remains, the backdoor Roth calculation may become much cleaner.
This is plan-dependent. Some 401(k)s accept rollovers; others do not. Some accept only certain types of IRA assets. Always verify before moving money.
Form 8606 Matters
Form 8606 tracks nondeductible IRA basis. If you make a nondeductible traditional IRA contribution and do not file Form 8606, your records can become messy. Years later, you may have trouble proving that part of an IRA distribution or conversion should not be taxed again.
For a backdoor Roth, Form 8606 generally reports:
- the nondeductible traditional IRA contribution
- your total traditional, SEP, and SIMPLE IRA year-end balance
- the Roth conversion
- the taxable and nontaxable portions
Tax software can handle this, but only if the inputs are correct.
Backdoor Roth vs Mega Backdoor Roth
The backdoor Roth IRA uses an IRA contribution and conversion. The mega backdoor Roth uses after-tax contributions inside a workplace retirement plan, then converts or rolls those after-tax dollars to Roth.
They are different strategies with different limits and plan requirements. A person may be able to use one, both, or neither.
Bottom Line
A backdoor Roth IRA can be valuable in 2026, but only when you understand the pro-rata rule. The strategy is cleanest when you have no pretax traditional, SEP, or SIMPLE IRA money at year-end.
If you do have pretax IRA balances, calculate the tax cost before converting. The conversion may still be worth doing, but it is not the nearly tax-free move many people expect.
Related Reading
Sources
- IRS, Publication 590-A
- IRS, Publication 590-B
- IRS, Form 8606 and instructions