Timely Medical Billing Laws in California: Deadlines and Disputes

California’s timely medical billing laws set two separate clocks: one for how quickly a provider must submit a claim after treatment, and one for how quickly the insurer must pay or contest it. The provider’s window runs from 90 days (for some contracted health plan claims) up to 12 months (for Medicare and workers’ compensation). The insurer’s window is typically 30 to 45 working days for health plans and 45 days for workers’ comp. Miss the provider deadline and the claim can be denied with no right to bill the patient; miss the insurer deadline and automatic penalties and interest kick in.

How Long a Provider Has to Submit a Claim

The clock starts on the date of service, or on the date of discharge for inpatient care. The deadline itself depends on what kind of coverage the patient has.

DMHC-Regulated Health Plans

For plans overseen by the California Department of Managed Health Care, non-contracted providers get at least 180 days from the date of service to submit a claim. Contracted providers may face a shorter window, as little as 90 days, if their contract with the plan sets that limit.¹ A claim filed after the deadline can be denied outright, and the provider has no legal right to bill the patient for the balance.

Medi-Cal

Medi-Cal has the tightest standard deadline. Providers must submit claims within six months of the month of service.² Claims filed between six and 12 months may still be accepted with a valid delay reason code and supporting documentation. Beyond 12 months, the provider needs a specific billing exception with attachments justifying the late submission. Without one of those qualifying reasons, the claim is rejected.

Medicare

Medicare follows the federal rule: claims must be filed no later than one calendar year after the date of service.³ If the deadline lands on a weekend or federal holiday, it extends to the next business day. Late Medicare claims are not reimbursed except in narrow circumstances such as retroactive entitlement or an administrative error by the government.

Workers’ Compensation

A provider treating an injured worker must submit an itemized bill to the employer or its insurer within 12 months of the date of service, or within 12 months of discharge for inpatient facility stays.⁴ Missing this deadline can forfeit the right to payment entirely.

How Long an Insurer Has to Pay or Contest a Claim

California doesn’t just tell providers when to bill. It also tells insurers when to pay.

For DMHC-regulated health plans, reimbursement is due within 30 working days of receiving a complete claim. For HMOs, the deadline is 45 working days. If the plan wants to contest or deny the claim instead, the same timelines apply, and the plan must give the provider written notice within that window.¹

For workers’ compensation, the employer or insurer must pay a medical bill within 45 days of receiving the itemized charges. To contest part of it, they must send written notice within 30 days explaining what’s disputed and why. Government employers get 60 days to pay.⁴

What Happens When a Deadline Is Missed

The consequence depends on which side ran out of time.

When a provider files late, the insurer can deny the claim, and the provider generally cannot then bill the patient for the amount the insurer refused. This is enforced strictly in Medi-Cal and in balance-billing situations. The provider absorbs the loss. Repeated late filings or billing violations can also draw scrutiny from the Department of Health Care Services, which audits and investigates fraud, waste, and abuse in the Medi-Cal program.⁵ Serious or repeated violations can lead to fines or exclusion from state-funded programs.

When a workers’ compensation insurer pays late, the penalty is automatic. Any amount not paid within the 45-day window must be paid at the applicable rate plus an additional 15 percent, along with interest at the same rate as civil judgments, running retroactively from the date the insurer first received the bill.⁴ The insurer avoids the penalty only by paying at the correct rate within 45 days and providing a written explanation of any contested items.

When the Standard Deadlines Bend

A handful of situations give providers more room than the standard timelines suggest.

Emergency Services

Hospitals must stabilize emergency patients without first asking about their ability to pay, and a health plan must cover all medically necessary pre-stabilization emergency care regardless of whether the provider is in network.⁶ Because emergency billing often involves out-of-network providers and delayed identification of the responsible insurer, timelines for these claims tend to run more flexibly in practice.

Retroactive Medi-Cal Eligibility

A patient who was uninsured when they received care but later qualifies for Medi-Cal can have expenses covered retroactively for up to three months before their application date, provided they would have been eligible during those months.⁷ Providers in this situation can submit claims beyond the standard six-month deadline because the patient’s coverage didn’t exist at the time of service.

Circumstances Beyond the Provider’s Control

The DMHC and DHCS review extension requests on a case-by-case basis for events like natural disasters, system outages, or administrative errors by the insurer. The provider needs documentation tying the delay to the specific circumstance rather than to ordinary billing inefficiency.

Good Faith Estimates Before Care

One deadline runs before any bill exists. Under the federal No Surprises Act, any California provider scheduling a service for an uninsured or self-pay patient must give a good faith estimate of expected charges. The timing depends on how far out the service is scheduled:

Scheduled three to nine business days out: estimate within one business day of scheduling.
Scheduled 10 or more business days out: estimate within three business days of scheduling.
Patient requests an estimate: the provider has three business days to deliver it.

If the scope of care changes after the estimate is issued, the provider must send an updated estimate at least one business day before the scheduled service.⁸ A patient who later receives a bill substantially exceeding the estimate can initiate a federal dispute resolution process. This requirement applies to all providers in California, not just those billing insurance.

Disputing a Late or Incorrect Bill

Provider Disputes with Health Plans

DMHC-regulated plans must maintain a dispute resolution process that is fast, fair, and cost-effective. They cannot impose a dispute-filing deadline shorter than 365 days from the plan’s payment decision, or from the date the plan was supposed to respond if it never did.⁹ HMOs have 45 working days to resolve provider disputes; other plans have 30 working days.¹

Provider Disputes in Workers’ Compensation

A provider who disagrees with the amount paid on a workers’ compensation bill can request a second review within 90 days. The insurer must issue a final written determination within 14 days and pay any undisputed balance within 21 days of receiving the second-review request.⁴

Patient Disputes

If you are covered by a DMHC-regulated plan, start with the plan’s internal grievance process. If the plan doesn’t respond within 30 days, or you disagree with the outcome, you can file a complaint or request an independent medical review through the DMHC.¹⁰ The independent medical review process brings in a neutral third party to evaluate whether the charges or the coverage denial were appropriate.

Where to Complain If a Direct Dispute Stalls

When talking to the provider or insurer goes nowhere, several agencies can step in.

The Department of Managed Health Care handles complaints about health plans licensed under the Knox-Keene Act, which covers most HMOs and many PPOs in California. The DMHC Help Center takes complaints about improper billing, claim denials, and coverage disputes, and the agency can investigate, impose fines, and order plans to reimburse wrongful charges.¹⁰
The California Department of Insurance covers health insurance policies not regulated by the DMHC, typically traditional indemnity plans and some PPOs. Its Consumer Services Division reviews billing complaints and enforces state insurance laws.
The Medi-Cal Managed Care Ombudsman helps Medi-Cal beneficiaries resolve problems with their managed care plans. Balance billing Medi-Cal recipients is illegal in California, and patients who receive bills for amounts beyond their cost-sharing should report the provider.¹¹¹²
For Medicare billing complaints, call 1-800-MEDICARE and ask to be directed to the Medicare Beneficiary Ombudsman, which helps resolve complaints, grievances, and coverage disputes.¹³

Filing a regulatory complaint doesn’t prevent you from pursuing other legal remedies, and it often resolves the problem faster than litigation, particularly when the issue is a clear statutory deadline that one side missed.

1
Cornell Law Institute. California Code of Regulations Title 28 1300.71 – Timely Payment of Claims
2
Legal Information Institute. California Code of Regulations Title 22 51008 – Bills for Service
3
eCFR. 42 CFR 424.44 – Time Limits for Filing Claims
4
California Legislative Information. California Labor Code Section 4603.2
5
CA.gov. Audits and Investigations – DHCS
6
New York Codes, Rules and Regulations. 28 CCR 1300.71.4 – Emergency Medical Condition and Post-Stabilization Responsibilities
7
Legal Information Institute. California Code of Regulations Title 22 50197 – Retroactive Eligibility
8
eCFR. 45 CFR 149.610 – Requirements for Provision of Good Faith Estimates
9
Cornell Law Institute. California Code of Regulations Title 28 1300.71.38 – Dispute Resolution Mechanism
10
California Department of Managed Health Care. How to File a Complaint
11
California Department of Health Care Services (DHCS). Medi-Cal Managed Care and Mental Health Office of the Ombudsman
12
DHCS – CA.gov. Balance-Billing
13
Centers for Medicare & Medicaid Services. Medicare Beneficiary Ombudsman (MBO)