There's no fixed maximum for a UK sick note — GPs decide duration based on your condition, issuing fit notes for up to 3 months at a time before reviewing.
Medically reviewed by Dr Sulaiman Shah , MBChB BMedSci, MRCGP — General Practitioner and founder of The GP Clinic.Last reviewed: 15 September 2026
There is no single expiry rule for medical certificates in the UK. A fit note lasts exactly as long as the dates written on it. A seafarer medical certificate runs for two years. A travel certificate is often only accepted if it was issued within the last 30 days.
Which one you’re holding determines everything, so this guide covers each type separately — what it’s for, how long it lasts, and what to do once it runs out.
| Certificate type | Typical validity | Who sets the period |
|---|---|---|
| Fit note (sick note) | The exact dates written on the note | Issuing clinician |
| Seafarer medical | 2 years from issue, sometimes shorter | MLC 2006 / examining doctor |
| Disability certificate | Often 12–24 months | The organisation requesting it |
| Travel or insurance | Often within 30 days of travel | Airline, cruise line or insurer |
| Occupational health | Until the review date stated on it | Assessing clinician |
A fit note — still called a sick note by most people — confirms that you’re either not fit for work, or that you could work with some adjustments. It’s issued by a GP, and in some settings by a nurse, pharmacist, or other authorised clinician.
It covers a specific window of time written directly on the document. If it says you’re unfit for work from the 5th to the 26th, that’s the exact period it covers. Once that date passes, the note has done its job. If you’re still unwell, you’ll need a fresh assessment and a new note for the period ahead.
A few practical points worth knowing:
Yes — a certificate can stop being usable before its stated expiry date if the situation it describes no longer matches reality.
If your health has changed significantly since it was issued — you’ve worsened, been newly diagnosed, or actually recovered to the point where your day-to-day situation looks different — the certificate may no longer reflect where you currently stand. Most organisations reviewing this kind of documentation want to know your present situation, not a snapshot from a few weeks ago. A document that no longer matches is likely to be questioned.
The purpose matters as much as the date. A certificate that fully satisfies one application may not meet the requirements of a different one, even while it’s technically still in date. Always check what the requesting organisation actually needs before assuming an existing certificate will cover it.
For anyone working at sea, a medical certificate isn’t optional — it’s a legal requirement under the Maritime Labour Convention 2006, which governs working conditions for seafarers internationally. Every crew member on a commercial vessel needs a currently valid one.
The standard validity period is two years from the date of issue, as set out in Standard A1.2 of the Maritime Labour Convention 2006. It can run shorter where age or specific health findings lead the examining clinician to recommend more frequent reassessment. Whatever expiry date is printed on the certificate is the one that counts.
An expired certificate is treated exactly the same as not having one at all — you can’t legally board a commercial vessel without one that’s currently in date. Approved maritime medical examiners can usually fit appointments within a few days, but that still means planning ahead rather than leaving it to the last minute.
A disability medical certificate confirms the nature and impact of a long-term health condition. People need these for a wide range of things — supporting a benefits claim, applying for a Blue Badge, requesting reasonable adjustments at work or in education, and similar situations.
How long one stays usable depends on two things: the nature of the condition, and what the certificate is actually being used for.
Where a condition is permanent and well-established — diagnosed for years, unlikely to change in its fundamental nature — somewhat older documentation may still be accepted by some organisations, provided it still accurately reflects the current situation. But for conditions that fluctuate, or where the practical impact on daily life has shifted, more recent documentation is almost always preferred, and often specifically required.
Every organisation sets its own requirement for how recent the certificate needs to be. Some accept documentation from within the last two years; others want something from the last twelve months; for applications assessing financial support, very recent documentation is often essential. The only reliable way to know is to check what the specific organisation requires before you book the appointment, not after.
These come up most often for long-haul flights, cruise travel, or any journey made after a recent procedure or illness. Airlines, cruise lines, and insurers each set their own requirements, and those requirements vary considerably.
A commonly seen rule is a certificate dated within 30 days of travel, though some organisations want something within a much tighter window — sometimes seven to ten days before departure. There’s no standard that applies across the board, so the only way to get this right is to ask whoever is requesting the certificate exactly what they need, before you book anything. Turning up with a certificate written eight weeks earlier and being told it falls outside the accepted window is a completely avoidable problem.
Occupational health assessments produce certificates used for fitness-to-work clearance, return to work after illness or injury, and role-specific health requirements or adjustments.
Validity tends to reflect the assessing clinician’s judgement about how long their findings will remain accurate. For roles with ongoing safety requirements — healthcare, transport, work involving particular hazards — periodic reassessment is built into the process, with each certificate carrying its own review date. For return-to-work assessments, the certificate typically runs until the review point the clinician considers appropriate given the expected recovery.
Fit notes cover defined periods set by the clinician. Seafarer certificates run for two years as standard. Disability certificates vary by condition and by what the receiving organisation asks for. Travel certificates depend entirely on the airline, cruise line or insurer’s own window. The rule for one type of certificate rarely carries over to another — that mismatched assumption is exactly what leads to needing a replacement at the worst possible moment.
Whatever certificate you’re dealing with, the approach is the same: check the specific requirement early, keep track of the expiry date, and don’t assume a document written for one purpose will automatically work for another.
Yes, though how quickly depends on the type. A fit note expires on the date written on it; a seafarer certificate after two years; travel certificates are often only valid within a short window before departure. A certificate can also stop being valid early if your circumstances have genuinely changed since it was issued.
It depends entirely on the type and purpose. A fit note covers only the exact dates the clinician has written on it — commonly a few days to a few weeks, depending on the clinician’s assessment of the condition.
A GP can issue a fit note covering whatever period is clinically appropriate — from a few days up to several months for a long-term condition. There’s no fixed maximum for a first note; it depends on the clinician’s assessment.
It can, but only where the clinician has evidence to support it, and there’s no fixed legal limit. In practice most GPs are comfortable backdating by a couple of weeks; anything longer needs stronger supporting evidence and remains a clinical judgement, not an automatic right.
It confirms you’re medically fit to return to or continue working, sometimes with adjustments noted. Validity is set by the assessing clinician and is usually tied to a review date rather than a fixed period.
