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Mega Backdoor Roth: After-Tax 401(k) to Roth Conversion
How the mega backdoor Roth works — contribute after-tax 401(k) dollars and convert to Roth for extra tax-free savings.
July 9, 20267 min readBy MyWealthForge
Key Takeaways
- 1Total 401(k) limit (2025): $69,000 including employer match.
- 2After maxing $23,500 pre-tax/Roth, add after-tax contributions.
- 3Convert after-tax portion to Roth IRA or in-plan Roth.
- 4Requires employer plan to allow after-tax contributions + in-service withdrawals.
The mega backdoor Roth can funnel $40,000+ per year into Roth accounts — but few employers support all required plan features.
Know 401(k) limits first.
How It Works
Max regular 401(k) at $23,500. Add after-tax contributions up to $69,000 total cap. Immediately convert to Roth.
Earnings between contribution and conversion are taxable.
Check Your Plan
Ask HR: after-tax contributions allowed? In-service withdrawals? In-plan Roth conversion?
Alternative: backdoor Roth IRA.
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