What this is
MegaBackdoorCheck answers two questions: does your 401(k) plan support the Mega Backdoor Roth, and how much room do you have this year? It does so with a deterministic SPD decoder and a §415(c) capacity calculator that both run entirely in your browser. Nothing you enter is sent anywhere or stored.
How we keep it honest
- No fabricated limits. Every IRS dollar figure is transcribed from the official COLA notice with a primary-source link and a last-verified date. Published figures are never edited in place — a new tax year adds a new entry.
- Deterministic math. The decoder verdict and the capacity number are pure functions of your inputs, unit-tested against IRS-anchored worked examples. If the calculator ever disagreed with a worked example, the build would fail.
- No fake reviewer. YMYL financial content needs a credentialed reviewer. Until a real CPA, CFP, or Enrolled Agent is engaged, the site says so plainly rather than inventing a name.
- Illustrative employer registry. Plan features change. The registry ships as illustrative archetypes — not unverified claims about a specific company — until each entry is verified against a primary source.
Reviewer
We are recruiting a credentialed CPA / CFP / Enrolled Agent with a 401(k)-after-tax specialty to review statute interpretation and the Form 8606 walkthrough. Until that reviewer is engaged and named here, treat every page as educational and confirm specifics with your own advisor.
Independent CPA / CFP review in progress
Who owns it
MegaBackdoorCheck is an independent, US-market educational resource. It is an information hub, not a CPA firm, financial advisor, or law firm. The operating entity will be listed in the footer once registered.