US Retirement - Mega Backdoor Roth
Mega Backdoor Roth Calculator
Already maxing your 401(k)? There is still $30k+/year of Roth space hiding in the IRS rules. Find your mega backdoor Roth room for 2026 and project its tax-free growth. Free, no sign-up.
1. Nominal APY vs. Real Post-Inflation Yield
A common pitfall in yield farming and staking is prioritizing high nominal APY percentages without factoring in baseline network token inflation. For instance, if a network offers 14% nominal staking rewards but dilutes circulating supply by 10% annually, your real purchasing power expansion is only ~3.6%.
2. Liquid Staking Derivatives (LSTs) & Capital Efficiency
Liquid staking protocols (such as Lido stETH, Rocket Pool rETH, and JitoSOL) allow institutional participants to maintain yield generation while retaining liquidity for DeFi lending and liquidity provision. However, LSTs introduce smart contract and depeg risk that must be modeled into portfolio variance.
The Mega Backdoor Roth: $37,500/Year of Extra Roth Space
The regular backdoor Roth gets you $7,500/year. The mega backdoor Roth can add tens of thousands more — by filling the gap between your normal 401(k) contributions and the IRS total limit with after-tax dollars, then converting them to Roth.
How the math works (2026)
The 2026 annual additions limit is $72,000. Subtract your $24,500 elective deferrals and, say, $10,000 of employer contributions: $37,500 of after-tax room remains. Contribute it after-tax and convert to Roth (in-plan conversion or in-service withdrawal), and that money grows tax-free forever. At 7% for 20 years, $37,500/year becomes about $1.54 million — all Roth.
Two plan features you must have
Not every 401(k) allows this. You need (1) after-tax (non-Roth) contributions beyond the $24,500 deferral limit, and (2) in-service Roth conversions or in-service withdrawals while still employed. Check your plan's summary description or ask HR — large tech employers commonly offer both.
Watch outs
- Convert quickly: earnings before conversion are taxable, so convert each contribution promptly (many plans offer automatic Roth conversion).
- Highly compensated testing: some plans restrict after-tax contributions for HCEs.
- Do the basics first: 401(k) to the full match, then HSA, then regular backdoor Roth — the mega backdoor is the last bucket to fill, not the first.
Model the earlier buckets with our 401(k) calculator and HSA calculator, then use this page for the overflow.
Mega Backdoor Roth: Frequently Asked Questions
What is a mega backdoor Roth?
After-tax 401(k) contributions (beyond the $24,500 deferral limit) that are converted to Roth, using the gap up to the $72,000 annual additions limit. It can add $30k+/year of Roth space.
How much can I put in a mega backdoor Roth for 2026?
$72,000 minus your elective deferrals minus employer contributions (plus catch-up if 50+). Example: $72,000 - $24,500 - $10,000 = $37,500.
Does my 401(k) plan allow mega backdoor Roth?
Only if it permits after-tax contributions AND in-service Roth conversions or withdrawals. Check your summary plan description or ask HR.
Is the mega backdoor Roth legal?
Yes — it uses IRS-sanctioned contribution and conversion rules. Convert promptly so pre-conversion earnings (taxable) stay near zero.
Mega backdoor vs regular backdoor Roth?
Regular backdoor: $7,500/year through a Traditional IRA conversion (for high earners over Roth income limits). Mega: up to ~$37,500/year through your 401(k). They stack.