How 2027 401(k) limits get set: Milliman’s $25,500 forecast still waits on September CPI

What happened

Brian Anderson at 401(k) Specialist, writing Sept. 14, 2026, walks Milliman’s penultimate 2027 IRS Limits Forecast after August Consumer Price Index data landed. Milliman projects the maximum 401(k), 403(b), and 457 elective deferral will rise by $1,000 — from $24,500 in 2026 to $25,500 in 2027. That is the Finance filing: how the COLA machine works, not a buy-or-sell tip.

The same report flags a live fork. If the CPI increase in September 2026 is less than 0.04%, the deferral limit may only climb to $25,000, and the regular age-50+ catch-up may stay at $8,000 instead of rising to $8,500. Milliman also projects the defined-contribution annual-additions limit at $75,000 (up $3,000 from $72,000), the ages 60–63 “super” catch-up at $11,750, and Emergency Savings Account limits at $2,700. Official IRS numbers typically arrive in late October or early November after September CPI prints on October 14; the 2026 limits were announced November 13, 2025. Bright chart colors, white gutters, cartoon piggy only. Educational — not investment advice and not market speculation.

September is the last CPI month in the statutory window before the IRS notice. Readers get the $24,500→$25,500 central case, the <0.04% CPI fork to $25,000, catch-up $8,000 vs $8,500, DC additions $75,000, ESA $2,700, the October 14 CPI date, and the usual November release pattern — an explainer of limits math, not a prediction of returns.

Why it matters

Retirement plan ceilings are a schedule written by statute and inflation indexes, not a hot take. Payroll systems, plan documents, and employee portals have to update before January. Vanguard’s 2026 How America Saves report, cited in the piece, estimated about 14% of DC participants already hit the elective-deferral maximum, so a higher cap can matter for those savers and for employer match budgets. Color on the fork between $25,000 and $25,500. White gutters. Readers get the Milliman table logic, the September CPI swing factor, and the source URL — education only.

Conclusion

Milliman’s late-cycle forecast points to a $25,500 elective-deferral limit for 2027 — with a live September CPI fork that could hold the number at $25,000 — and the IRS still has to publish the official notice after October 14 inflation data, per 401(k) Specialist. This is education about how contribution limits are calculated, not a recommendation. Source: https://401kspecialistmag.com/2027-401k-contribution-limit-projected-to-rise-to-25500/