Arizona Medical Malpractice Statute of Limitations: Deadlines and Exceptions

The Arizona medical malpractice statute of limitations gives you two years to file suit, measured from the date you discovered, or reasonably should have discovered, that negligent medical care caused your injury. That deadline comes from A.R.S. § 12-542.¹ Miss it and the court will dismiss your case regardless of how strong the underlying claim is. But two years is only the headline number. Shorter preliminary deadlines apply to some defendants, longer deadlines apply to some patients, and a separate procedural rule can sink an otherwise timely lawsuit if you’re not ready for it.

The Two-Year Deadline and When It Starts

A.R.S. § 12-542 treats medical malpractice as a type of personal injury action and gives it the same two-year window. Once two years pass after the cause of action accrues, the defendant can move to dismiss and the court will grant that motion. There is no judicial discretion, no grace period, and no equitable workaround built into the statute itself.¹

The two-year period does not necessarily begin on the date of the medical error. Arizona courts apply the “discovery rule,” a framework the Arizona Supreme Court established in Kenyon v. Hammer (1984). Under that rule, the clock starts when you know, or reasonably should know, both that you were injured and that the injury was caused by negligent medical care.

This matters when harm is hidden or slow to show. A misread pathology slide, a missed cancer diagnosis, or a surgical sponge left inside the body may produce no obvious symptoms for months or years. In those cases, the two-year clock begins on the date you actually learned about the problem, or the date a reasonably diligent person in your position would have learned about it.¹

The catch is that you carry the burden of proof. If you file more than two years after the medical event itself and lean on the discovery rule, you need to show you could not have discovered the malpractice earlier through reasonable effort. Courts look at whether you followed up on symptoms, sought second opinions when something felt wrong, and paid attention to the information your providers gave you. Not knowing is not enough if a court concludes you should have known.

Arizona also has no statute of repose for medical malpractice. Many states impose an absolute outer deadline measured from the date of the medical act itself, often six, eight, or ten years, which cannot be extended by discovery or tolling. Arizona does not. In theory, the discovery rule can push the filing deadline well past two years from the date of treatment, as long as you can show that a reasonable person would not have discovered the injury sooner.

When the Deadline Is Shorter Than Two Years

If the healthcare provider is a public entity or public employee, such as a county hospital or a doctor at a state-run facility, a much tighter preliminary deadline governs the case. A.R.S. § 12-821.01 requires a formal notice of claim within 180 days after the cause of action accrues. Miss that window and the claim is permanently barred, even if the two-year statute of limitations has not yet expired.²

The notice of claim is not a lawsuit. It is a written document that must include facts explaining the basis for liability and a specific dollar amount for which the claim can be settled, along with supporting facts for that amount. You file it with the person authorized to accept service for the public entity under Arizona’s civil procedure rules. If the public entity does not respond in writing within 60 days, the claim is automatically deemed denied, and you can proceed to file suit. For accrual purposes, the statute uses the same discovery-based trigger: when you realize you have been damaged and know or reasonably should know the cause.²

A federal facility is a different track altogether. If your claim involves a federal employee acting within the scope of their job at a VA medical center or Indian Health Service facility, Arizona’s state deadlines do not apply. The Federal Tort Claims Act governs instead. Under 28 U.S.C. § 2401(b), you must present a written administrative claim to the responsible federal agency within two years after the claim accrues. You cannot file a lawsuit first. If the agency denies the claim, you then have six months from the date the denial is mailed to sue in federal court. If the agency does not act within six months, you can treat that silence as a denial and file.³

One critical difference: the FTCA does not toll the deadline for minors. A child injured at a VA hospital faces the same two-year administrative filing deadline as an adult. Mistaking which system applies is a common way to lose a viable claim, because the administrative exhaustion requirement has no exceptions.

When the Deadline Runs Longer Than Two Years

A.R.S. § 12-502 pauses the statute of limitations for people who cannot protect their own legal interests. If the injured patient was under 18 when the malpractice occurred, the two-year period does not start running until they turn 18. That effectively gives a minor until their 20th birthday to sue.⁴

The same rule applies to individuals who are of “unsound mind” when the cause of action accrues. The time spent in that condition does not count toward the two-year deadline. Once the disability ends, the person gets the full two years. These tolling rules operate alongside the discovery rule, so a minor whose injury also could not have been discovered until later benefits from both.⁴

For public entity claims, § 12-821.01 gives minors and incapacitated persons 180 days from the date their disability ends, rather than from the date of the underlying negligence.²

Wrongful death from medical malpractice also falls under § 12-542’s two-year deadline, but the clock starts from the date of death rather than the date of the underlying negligent act. If a patient received negligent care in 2023 and died from its consequences in 2025, the family has until 2027 to sue, even though more than two years have passed since the original error.¹

The Expert Affidavit That Must Travel With Your Lawsuit

Filing on time is not enough on its own. A.R.S. § 12-2603 adds a procedural layer that catches many claimants off guard. When you assert a medical malpractice claim, you or your attorney must file a written certification stating whether expert testimony is needed to prove the standard of care or liability. In the vast majority of malpractice cases, it is.

If expert testimony is needed, you must serve a preliminary expert opinion affidavit along with your initial disclosures under Arizona’s civil procedure rules. The affidavit has to include the expert’s qualifications, the factual basis for each claim, the specific acts or omissions that violated the standard of care, and how those acts caused your damages.⁵

Failing to serve the affidavit when one is required results in dismissal. The dismissal is without prejudice, so you can refile, but only if the statute of limitations has not run out in the meantime. Finding a qualified medical expert, having them review the records, and getting a proper affidavit drafted takes time, which is why this work needs to be happening well before the two-year mark approaches.⁵

Working Backward From the Deadline

Meeting the two-year deadline in practice requires more lead time than most people assume. A realistic sequence looks like this:

Request complete medical records from every provider involved. Requests can take weeks, and providers sometimes delay.
Line up an expert review. A qualified medical professional has to read the records and form an opinion before the § 12-2603 affidavit can be drafted. This step alone often takes months.
Identify the correct defendant early. If the provider is a public entity, the 180-day notice deadline is already running. If a federal facility is involved, the FTCA administrative process controls. Getting the defendant category wrong wastes critical time.
If you are relying on late discovery, gather evidence showing when and how you learned about the injury. The burden is yours.

Waiting until the last few months to begin is the single most common reason otherwise valid Arizona malpractice claims fail. The statute of limitations is a hard wall, and the preparatory work needed to clear it takes longer than most patients expect.

1
Arizona Legislature. Arizona Code 12-542 – Injury to Person; Injury When Death Ensues; Two Year Limitation
2
Arizona Legislature. Arizona Code 12-821.01 – Authorization of Claim Against Public Entity, Public School or Public Employee
3
Office of the Law Revision Counsel. 28 USC 2401 – Time for Commencing Action Against United States
4
Arizona Legislature. Arizona Code 12-502 – Effect of Minority or Insanity
5
Arizona Legislature. Arizona Code 12-2603 – Preliminary Expert Opinion Affidavit