Tools · Mega Backdoor Roth

Mega backdoor Roth
capacity.

If your 401(k) plan allows after-tax contributions and in-service rollovers, you can shelter tens of thousands more per year in a Roth wrapper than the standard limit. This tool shows your remaining capacity.

This page covers US-specific 401(k) rules. The mega backdoor Roth is unique to the US 401(k) / 403(b) / solo 401(k) structure. It does not exist in other countries' workplace retirement systems.

Age 50+ unlocks catch-up contributions.

2026 limit: $24,500 ($32,000 with 50+ catch-up).

Check with your plan administrator whether both (a) after-tax contributions are allowed, and (b) in-service rollovers or in-plan conversions are allowed. Without both, the mega backdoor is not available.

YOUR MEGA BACKDOOR CAPACITY
$0
per year of additional tax-free savings room.
TOTAL 401(K) LIMIT
$72,000
YOUR CONTRIBUTION
$0
EMPLOYER MATCH
$0
REMAINING CAPACITY
$0
LIFETIME IMPACT
Enter values to see projection.
What this tool assumes
  • 2026 total 401(k) contribution limit (415(c)): $72,000; catch-up at 50+ adds $8,000 for $80,000 total.
  • 2026 employee elective-deferral limit (402(g)): $24,500; catch-up at 50+ adds $8,000 for $32,500 total.
  • Mega backdoor is only possible if your plan allows after-tax contributions and in-service conversions or rollovers.
  • After-tax contributions can exceed the employee contribution limit up to the total plan limit.
  • In-service rollover or in-plan conversion moves after-tax dollars to Roth immediately; earnings before the conversion are taxable.

The mega backdoor Roth is one of the most powerful retirement tools available to US W-2 employees. Educational only; not financial advice.

Related

→ Mega backdoor Roth guide → Backdoor Roth IRA → Roth vs Traditional calculator
HOW THIS IS CALCULATED

This tool runs entirely in your browser — no data is sent to any server. All formulas use standard financial math. Verify the methodology or inspect the source code in your browser's dev tools.