How Long Do You Have to Make a Negligence Claim?
You usually have three years to bring a medical negligence claim, under the Limitation Act 1980. The three years runs from the date of the negligent treatment, or from the later date you first realised or reasonably should have realised that the treatment had caused you significant harm. Different rules apply to children, to people who lack mental capacity, and to claims following a death.
The time limits at a glance
An adult with mental capacity - 3 years from the treatment, or from the date of knowlegde if later
A child - Until their 21st birthday - the clock only starts at 18
Someone who lacks mental capacity - No time limit while capacity is absent
Family or the estate after a death - 3 years from the date of death, or from their date of knowledge
Anyone outside the limit - A court has a discretion to allow the claim - but is is rarely exercised
When does the clock actually start?
For straightforward cases it starts on the day the negligence happened - a surgical error during an operation, for example, where the harm is obvious straight away.
Often, though, harm is not obvious at the time. That is why the law uses a second starting point: your date of knowledge.
This is the date you first knew, or could reasonably have been expected to know, three things:
That the injury was significant - Serious enough that you would reasonably consider it worth claiming for.
That it was attributable to the treatment
Who was responsible
Importantly, you do not need to have known that what happened amounted to negligence in law. Knowing that the harm was connected to your treatment is enough to start the clock , the legal analysis comes later.
Example - knowledge on the day. A patient suffers nerve damage during an operation and is told about it before discharge. The three years runs from the date of the surgery, because the harm and its link to the treatment were known immediately.
Example - knowledge years later. A scan taken in 2021 shows an abnormality that is not acted on. The patient feels fine and knows nothing about it. In 2025 a second scan leads to a diagnosis, and the earlier missed finding comes to light. The three years is likely to run from 2025, not 2021 because that is when the patient could reasonably have known the harm was linked to the earlier care.
What if the deadline has passed?
It is still worth asking. Section 33 of the Limitation Act 1980 gives a court a discretion to allow a claim to proceed out of time where it is fair to both sides.
A court weighs up matters including:
How long the delay was, and the reason for it
Whether the evidence records, witnesses, expert opinion is still reliable
How promptly the claimant acted once they knew they might have a claim
Whether they had already sought medical or legal advice
This discretion is genuinely available, and it is exercised in the right circumstances. But it is unpredictable, argued case by case, and adds cost and uncertainty to a claim. It should never be treated as a fallback for leaving things late.