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Private vs NHS sick notes: what’s the difference and which do you need?

Sick Note Guide

When you need medical evidence for your employer, it is not always clear whether you need an NHS sick note, a private medical certificate, or whether one is even required at all. This guide explains the difference, when each applies, and which one you actually need.

  • ✔Explains the legal difference between NHS fit notes and private medical certificates
  • ✔Clarifies which document you need based on your situation
  • ✔Covers cost, availability, and what each document is accepted for
  • ✔Explains when a private sick note is the only option available

The Basics

NHS Fit Note vs Private Medical Certificate: What Is Each One?

There are two distinct types of sick note in the UK. They are issued by different routes, serve different legal purposes, and are not always interchangeable.

NHS

Fit Note (Med3)

Also called
Statement of Fitness for Work, sick note
Issued by
NHS GP, hospital doctor, nurse, physio, pharmacist
When required
After 7 consecutive days of sickness absence
Cost
Free from NHS for absences over 7 days
Used for
Statutory Sick Pay (SSP), long-term absence, DWP benefits
Legal form
Official government Med3 form

Private

Private Medical Certificate

Also called
Doctor’s letter, private sick note, medical letter
Issued by
GMC-registered doctor via private practice or online service
When required
Any duration — including absences under 7 days
Cost
Fee charged; varies by provider
Used for
Employer requests, early evidence, universities, insurers, cancellations
Legal form
Signed clinical letter on professional headed paper

Which One Do You Need?

NHS Sick Note or Private Medical Certificate — Which Applies to You?

The right document depends on how long you have been off work, what your employer is asking for, and what the certificate will be used for.

Off for more than 7 days

You need an NHS fit note (Med3). This is free from your GP or another registered healthcare professional and is required for Statutory Sick Pay claims.

Off for 7 days or fewer

You can self-certify. Your employer cannot legally require a fit note. If they do request early medical evidence, a private medical certificate from a GMC-registered doctor can fulfil this.

University, insurers, or cancellations

For student sick notes, travel insurance claims, gym cancellations, or event refunds, a private medical certificate is the appropriate document. An NHS fit note is not usually required for these purposes.

When Private Is the Only Option

Situations Where a Private Medical Certificate Is the Right Choice

There are a number of common circumstances where an NHS fit note is either not available or not appropriate — and a private medical certificate from a GMC-registered doctor is the correct route.

1

Your employer requests early evidence (under 7 days)

Some employers — particularly during probationary periods or for employees with a pattern of short-term absence — may request medical evidence before the seven-day NHS threshold. In this case, a private sick note for work issued following clinical review is the standard solution. NHS GPs are not obliged to issue a Med3 for absences under seven days.

2

You cannot get a GP appointment in time

NHS appointment availability varies significantly across the UK. If you need documentation promptly and cannot secure a GP slot, an online private medical service staffed by GMC-registered doctors offers a clinically reviewed alternative. Certificates are not automatically issued — each application is subject to clinical review.

3

The certificate is for a non-employment purpose

NHS fit notes are designed specifically for workplace sickness absence and SSP. For university extenuating circumstances, travel cancellation certificates, gym membership cancellations, or similar — a private medical letter is the appropriate document and the only type most institutions will accept for these purposes.

Validity & Acceptance

Are Private Medical Certificates Accepted by Employers?

A private medical certificate issued by a GMC-registered doctor carries the same clinical authority as one issued in an NHS setting. The doctor is subject to the same professional and regulatory obligations regardless of whether they practise privately or within the NHS.

Most UK employers accept private medical certificates for short-term absences and early evidence requests. Acceptance is ultimately at the employer’s discretion — their sickness absence policy should be checked in advance.

A private medical certificate is valid and professionally credible when it is:

✔Issued by a GMC-registered doctor following individual clinical review
✔Signed, dated, and presented on professional headed documentation
✔Based on disclosed medical history and clinical assessment — not automatically generated
✔Issued only where clinically appropriate — applications may be declined

Clinical Standards

Clinical Review & Eligibility

Private medical certificates issued through MedicalCert are reviewed individually by GMC-registered UK doctors in accordance with UK clinical standards. Every application is assessed on its own merits.

✔All documentation reviewed by GMC-registered doctors
✔Certificates are not automatically generated
✔Applications may be declined if clinically inappropriate
✔Each request is subject to the reviewing doctor’s independent clinical judgement
✔Patient information handled in accordance with UK data protection standards

Important Limitations

Limitations & When In-Person Care Is Required

A private medical certificate is not a replacement for NHS care or clinical diagnosis. The following situations require in-person or NHS assessment:

›Emergency or urgent medical conditions — call 999 or attend A&E immediately
›Conditions requiring physical examination, diagnostic tests, or imaging
›Official DWP documentation — Med3 fit notes for Statutory Sick Pay must be issued by a registered NHS practitioner
›Employers who specifically require an NHS fit note rather than a private certificate

Final acceptance of any private medical certificate is determined by the employer, educational institution, insurer, or other third party. MedicalCert cannot guarantee acceptance by any third party.

FAQ

Frequently Asked Questions

What is the difference between an NHS sick note and a private medical certificate?
An NHS sick note (Med3 fit note) is the official government form issued free of charge by NHS practitioners for absences over seven days. It is required for Statutory Sick Pay and DWP benefit claims. A private medical certificate is issued by a GMC-registered doctor outside the NHS — typically for shorter absences, early employer evidence requests, or non-employment purposes such as university or insurance claims. Both carry clinical authority when issued by a registered doctor.
Can a private sick note be used for Statutory Sick Pay?
No. Statutory Sick Pay (SSP) claims require an official NHS Med3 fit note after the first seven days of absence. A private medical certificate cannot be used as a substitute for SSP purposes. However, for absences of seven days or fewer — where SSP does not yet apply — a private certificate may satisfy your employer’s request for early medical evidence.
Do employers have to accept a private sick note?
There is no legal obligation for employers to accept a private medical certificate, though most do — particularly for short-term absences or early evidence requests. Acceptance is at the employer’s discretion and subject to their own policy. If your employer specifically requires an NHS fit note, a private certificate will not substitute for it. Always check your employer’s sickness absence policy before proceeding.
Is a private sick note from an online doctor valid?
Yes, provided it is issued by a GMC-registered doctor following individual clinical review — not automatically generated. A certificate issued by a qualified UK-registered doctor carries the same professional standing regardless of whether the assessment took place in person or remotely. The doctor’s GMC registration number should appear on the documentation and can be verified on the GMC public register.
How much does a private medical certificate cost?
Costs vary by provider. NHS fit notes are free for absences over seven days. For absences of seven days or fewer, NHS GP practices may charge a fee — typically £15–£30. Online services offering GMC-reviewed private certificates typically charge from around £30–£50 depending on the type of certificate required. There is no fixed price set by any regulatory body.
Can a private sick note be backdated?
Yes, in some circumstances. A GMC-registered doctor can issue a certificate covering a period that has already elapsed, provided there is a clinical basis for doing so — such as medical history, prior consultation records, or other supporting evidence. Backdating is subject to clinical judgement and is not an automatic right. The doctor must be satisfied the period of incapacity is genuine and clinically supported.

Need a Private Sick Note from a UK Doctor?

If your employer has requested medical evidence or you need a private medical certificate reviewed by a GMC-registered doctor, MedicalCert can help — with no GP appointment needed.

Get a Private Sick Note →

Subject to clinical review. Applications may be declined if clinically inappropriate.

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