Capacity
How much Mega Backdoor Roth room do you have in 2026?
How much Mega Backdoor Roth room remains?
Deterministic §415(c) math with your numbers substituted in. Reproducible by hand and verifiable against the worked examples. Nothing is logged.
Live formula — §415(c) overall limit (2026)
room = §415(c)2026 − deferral − employer − after_tax
= $72,000 − $24,500 − $20,000 − $0
= $27,500
$27,500
$2,115 per pay period over 13 remaining periods
Already counted toward §415(c): $44,500 of $72,000
§415(c) capacity
The §402(g) age-50+ catch-up does not count against §415(c) — it sits on top of the annual-additions limit, so it is not subtracted here. Independent CPA / CFP review in progress
IRS limit table
The figures the calculator uses, transcribed from the IRS COLA notice for each year.
| Limit | 2026 | 2025 | Statute |
|---|---|---|---|
| §415(c) overall annual-additions limit | $72,000 | $70,000 | IRC §415(c)(1)(A) |
| §402(g) elective-deferral limit (Roth + pre-tax) | $24,500 | $23,500 | IRC §402(g)(1) |
| Age-50+ catch-up | $8,000 | $7,500 | IRC §414(v) |
| Age 60–63 higher catch-up | $11,250 | $11,250 | IRC §414(v)(2)(E)(ii) |
| Annual compensation limit | $360,000 | $350,000 | IRC §401(a)(17) |
Worked examples
Reconcile the calculator against these. Each is checked to the cent by the build's unit tests — if the calculator ever disagreed with one, the build would fail.
2026
Deferral maxed, $20k employer match
$27,500
$72,000 − $24,500 − $20,000 = $27,500 of remaining room.
2026
Smaller match, $5k after-tax already in
$33,500
$72,000 − $24,500 − $9,000 − $5,000 = $33,500 of remaining room.
2025
2025 limits, no after-tax yet
$35,000
$70,000 − $23,500 − $11,500 = $35,000 of remaining room.
Informational, not tax advice. Consult a CFP, CPA, or Enrolled Agent before acting on any Mega Backdoor Roth conversion. Plan rules are plan-document-specific — verify with your benefits administrator. IRS dollar limits change annually.