Mega Backdoor Roth
How the mega backdoor Roth works in 2026: after-tax 401(k) contributions up to the $72,000 limit, converting them to Roth, what your plan must allow, and your own contribution room.
Mega backdoor Roth calculator (2026)
How the mega backdoor Roth works
- Max out regular 401(k) deferrals ($24,500 in 2026).
- Add after-tax (non-Roth) contributions, if your plan allows them, up to the total annual additions limit of $72,000 (employee + employer, catch-ups not counted).
- Convert them to Roth quickly, by an in-plan Roth conversion or an in-service withdrawal to a Roth IRA, so future growth is tax-free.
Example: $24,500 of deferrals and an $8,000 match leave $39,500 of after-tax room. Earnings between contributing and converting are taxable when converted, so convert soon. Catch-ups ($8,000 at 50+, $11,250 at 60–63) are on top of the $72,000.
Does your plan allow it?
Only if the plan accepts after-tax contributions and allows in-plan conversions or in-service withdrawals; ask HR for the summary plan description. Highly compensated employees can be limited by nondiscrimination testing. For a regular backdoor Roth IRA, see the backdoor Roth IRA calculator.
Common questions
How much can I put in a mega backdoor Roth in 2026?
Up to $72,000 minus your deferrals and employer contributions; with $24,500 deferred and an $8,000 match, $39,500.
Do catch-up contributions count toward the $72,000?
No, catch-ups are added on top.
Is the mega backdoor Roth legal?
Yes, if your plan allows after-tax contributions and conversions.
Sources
More retirement calculators: Medicare Enrollment · Medicare Plan G · Net Unrealized Appreciation · Qualified Charitable Distributions
Related
General information, not financial, tax or legal advice. Check important numbers with the official source before acting on them.