Mega Backdoor Roth Calculator
High earners use the mega backdoor to push up to $46K into Roth via after-tax 401(k) contributions + in-plan conversion. Compute headroom available given existing contributions and employer match.
FINANCEHigh earners use the mega backdoor to push up to $46K into Roth via after-tax 401(k) contributions + in-plan conversion. Compute headroom available given existing contributions and employer match.
Detailed instructions, formula notes, and US-context guidance shown in the calculator above.
Mega Backdoor Roth Calculator
If your 401(k) plan allows after-tax contributions + in-plan Roth conversion (or in-service distribution), you can push up to $46.5K into Roth on top of the regular $23.5K limit. 2026 total limit: $70K ($77.5K at 50+).
Requires plan support: (1) after-tax (not Roth) contribution option, (2) in-plan Roth conversion OR in-service distribution. Only ~50% of 401(k) plans offer it. Convert FAST after each contribution to minimize earnings (taxable on conversion).