Mega Backdoor Roth After-Tax 401k 2027
Calculate mega backdoor Roth 2027 — after-tax 401k contributions + in-plan Roth conversion. Up to $46k/yr additional Roth. Plan support required.
How It Works
Standard time-value-of-money calculation. Compounding annually at stated rate. Pre-tax and post-tax shown.
2027 Updates
All IRS limits indexed annually for inflation. Use most recent year. Catch-up contributions for 50+ and new 60-63 super catch-up under SECURE 2.0.
Best Practices
Max tax-advantaged accounts first (401k match → HSA → Roth IRA → 401k). Then taxable brokerage. Bonds/CDs for stable yield component.
Common Pitfalls
Forgetting employer match (free money). Holding tax-inefficient funds in taxable. Withdrawing early (penalties). Not rebalancing.
Source: irs.gov Section 415(c) total contribution limits, financialsamurai.com. Last updated: May 2026.
Frequently Asked Questions
What's catch-up contribution?
Age 50+: extra contribution allowed. 401k catch-up $7,500. IRA catch-up $1,000. New super catch-up age 60-63 in SECURE 2.0.
Roth or Traditional?
Roth if you expect higher tax bracket in retirement. Traditional if expect lower. Most people benefit from MIX of both.
How to start?
Open account at Vanguard, Fidelity, or Schwab. Pick target-date fund or 3-fund portfolio. Auto-contribute every payday. Increase 1% per year.