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

Sick Note Guide

An NHS sick note (Med3 fit note) is a free government form issued by NHS practitioners for absences over seven days, used for Statutory Sick Pay and benefit claims. A private medical certificate is a signed clinical letter issued by a GMC-registered doctor for shorter absences, early employer evidence requests, university extenuating circumstances, and insurance claims. Both carry clinical authority when issued by a registered doctor, but they serve different purposes and are not interchangeable.

This guide explains the legal difference between these two documents, when each applies, and which one you actually need based on your situation.

✔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

Quick Reference

NHS Fit Note vs Private Medical Certificate: Side-by-Side Comparison

This table summarises the key differences between an NHS fit note and a private medical certificate in the UK.

Feature	NHS Fit Note (Med3)	Private Medical Certificate
Official name	Statement of Fitness for Work (Med3)	Private medical letter / doctor’s letter
Who can issue	NHS GP, hospital doctor, nurse, physiotherapist, pharmacist	Any GMC-registered doctor (private or online)
Cost	Free (for absences over 7 days)	Fee-based, typically £30 to £50
Absence duration	Required after 7 consecutive calendar days	Any duration, including under 7 days
Valid for SSP	Yes, required for SSP claims after day 7	No, cannot be used for SSP claims
Valid for DWP benefits	Yes (ESA, Universal Credit)	No
Employer acceptance	Legally recognised for absence and SSP	Widely accepted, at employer’s discretion
University / insurance	Not usually required for these purposes	Accepted by most universities and insurers
Can be backdated	Yes, at the GP’s clinical discretion	Yes, subject to clinical review and evidence
How to obtain	Book NHS GP appointment (in person or remote)	Apply online, reviewed by GMC-registered doctor

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 for the first seven days of absence, as confirmed by GOV.UK guidance on self-certification. 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.

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.

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 individual clinical review.

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 under the General Medical Council’s Good Medical Practice framework, 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. ACAS guidance confirms that employers can accept alternative medical evidence where an NHS fit note is not required. Acceptance is ultimately at the employer’s discretion, so 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, with applications declined where necessary

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 and the General Medical Council’s Good Medical Practice guidelines. 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 and benefit claims 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 (officially called a Med3 fit note or Statement of Fitness for Work) is a free government form issued by NHS practitioners for sickness absences lasting more than seven consecutive days. It is the required document for Statutory Sick Pay claims and DWP benefit applications including ESA and Universal Credit. A private medical certificate is a signed clinical letter issued by a GMC-registered doctor outside the NHS, typically used for shorter absences, early employer evidence requests, or non-employment purposes such as university extenuating circumstances and insurance claims. Both documents carry clinical authority when issued by a registered doctor, but they serve different legal purposes and are not interchangeable for SSP or benefit claims.

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 apply under the self-certification rules set out in the Employment Rights Act 1996, a private certificate may satisfy your employer’s request for early medical evidence.

Do employers have to accept a private sick note?

No. 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. ACAS guidance confirms that employers can accept alternative forms of medical evidence where an NHS fit note is not legally required. Acceptance is at the employer’s discretion and subject to their own sickness absence policy. If your employer specifically requires an NHS fit note, a private certificate will not substitute for it. Always check your employer’s policy before proceeding.

Is a private sick note from an online doctor valid?

Yes. A private sick note issued by a GMC-registered doctor following individual clinical review is valid and carries the same professional standing as one issued in person. The General Medical Council’s Good Medical Practice guidelines apply equally to remote and in-person consultations. The doctor’s GMC registration number should appear on the documentation and can be verified on the GMC public register at gmc-uk.org.

How much does a private medical certificate cost?

Private medical certificates typically cost between £30 and £50, depending on the provider and certificate type. NHS fit notes are free for absences over seven days. For absences of seven days or fewer, NHS GP practices may charge a private fee for issuing a letter, typically £15 to £30, as this falls outside their NHS contract obligations. 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.

Do I need a sick note for 1 day off work?

No. Under UK self-certification rules, you do not need any medical documentation for absences of seven calendar days or fewer. You can self-certify by completing an SC2 form or your employer’s own absence reporting process, as set out in GOV.UK guidance. However, some employers may request medical evidence even for short absences, particularly during probation or where there is a pattern of absence. In those cases, a private medical certificate from a GMC-registered doctor can provide the documentation your employer is asking for.

Can I use a private sick note for university?

Yes. Most UK universities accept private medical certificates as evidence for extenuating circumstances applications, deadline extensions, and assessment deferrals. An NHS fit note is designed for workplace absence and is not usually required by universities. A private certificate issued by a GMC-registered doctor following clinical review is typically the standard document universities request for medical-related academic adjustments.

What is the 7-day rule for sick notes in the UK?

The 7-day rule means that for the first seven consecutive calendar days of sickness absence (including weekends and non-working days), you can self-certify without any medical documentation. From day eight onwards, your employer can require an NHS fit note (Med3) from a registered healthcare professional. This rule is set out in GOV.UK’s statutory sick pay guidance and applies to all employed workers in the UK.

Sources

Sources & References

The information on this page is based on published guidance from UK government and professional bodies.

GOV.UK — Statutory Sick Pay: employee fitness

Official government guidance on fit notes, self-certification, and the 7-day rule for sickness absence.

gov.uk/statutory-sick-pay

ACAS — Managing sickness absence

Advisory guidance on employer obligations, medical evidence requirements, and sickness absence policies.

acas.org.uk

General Medical Council — Good Medical Practice

The professional standards framework governing all GMC-registered doctors, including clinical review and documentation obligations.

gmc-uk.org

Employment Rights Act 1996

Primary legislation establishing the framework for Statutory Sick Pay, self-certification, and employer obligations regarding sickness absence.

legislation.gov.uk

Clinically reviewed by Dr Maria Knobel

GMC Registration: 7495073 · Medical Director, MedicalCert

Last reviewed: May 2026

Not Sure Which Certificate You Need?

Use our certificate finder to identify the right document for your situation, whether you need evidence for your employer, university, insurer, or another purpose.

Find the Right Certificate →

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

Post Tags :

sick note