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By Eman Yazdchi, Esq. · Certified Specialist in Workers' Compensation Law, State Bar of California Board of Legal Specialization
In California, MMA (Maximum Medical Achievement) is the older term for what is now called MMI (Maximum Medical Improvement) — the date the injured worker's condition has stabilized so that permanent disability can be rated under California Labor Code §4660. Yazdchi Law, a Certified Specialist in Workers' Compensation Law firm, handles MMI rating disputes statewide. Request a free case review.
In California workers' compensation, MMI (Maximum Medical Improvement) — historically called MMA (Maximum Medical Achievement) and also known as "permanent and stationary" (P&S) — is the date the injured worker's medical condition has stabilized so that permanent disability can be rated under California Labor Code §4660. Before MMI, the worker is in active treatment and receives temporary disability under California Labor Code §4653; after MMI, the worker's condition is fixed for rating purposes and permanent disability indemnity under California Labor Code §4658 begins.
Under California Labor Code §4660, the date of MMI is set by the medical-legal evaluator — the Primary Treating Physician in an undisputed claim, or the Qualified Medical Evaluator under California Labor Code §4062.2 (represented worker) or Agreed Medical Evaluator (when parties stipulate) in a disputed claim. The evaluator issues a written report concluding the condition is permanent and stationary and assigning the AMA Guides 5th Edition Whole Person Impairment percentage.
When MMI is reached under California Labor Code §4660, three things shift: temporary disability under California Labor Code §4653 stops; permanent disability indemnity under California Labor Code §4658 begins on the §4660 rating schedule; and the worker becomes eligible for the Supplemental Job Displacement Benefit voucher under California Labor Code §4658.7 if the employer cannot accommodate any permanent work restrictions within 60 days.
Reaching MMI does not end the right to medical treatment under California Labor Code §4600. California workers' compensation provides future medical care for the life of the industrial injury — subject to Utilization Review under California Labor Code §4610 — unless the right is bought out through a Compromise & Release lump sum approved by the WCAB judge under California Labor Code §4906. A Stipulated Award keeps future medical care open after MMI; a C&R closes it.
Under California Labor Code §5410, a California injured worker has a five-year window from the date of injury to petition to reopen the claim for "new and further disability" — a worsening of the same industrial injury after MMI. The petition triggers a new California Labor Code §4660 rating. The §5410 reopening is distinct from the California Labor Code §5405 one-year original-filing deadline and protects workers whose California conditions deteriorate after the initial MMI determination.
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Tap to call →Last reviewed by Eman Yazdchi, Esq., May 2026.
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