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

Sick Note Guide

An NHS fit note, officially a Statement of Fitness for Work and still widely called a sick note or Med3, is issued free on the NHS by a doctor, nurse, occupational therapist, pharmacist, or physiotherapist. GOV.UK tells employers they can only ask for one if the employee is off work for more than 7 days in a row, and it is the usual evidence for Statutory Sick Pay and benefit claims. A private medical certificate is a signed clinical letter issued by a GMC-registered doctor, used for shorter absences, early employer evidence requests, university extenuating circumstances, and insurance claims. A private certificate is not a fit note, and it is accepted only where the organisation receiving it agrees to accept it.

This MedicalCert guide explains how the two documents differ, when each applies, and which one you are likely to need. MedicalCert connects patients with independent GMC-registered UK doctors who review each application individually and issue private medical certificates where clinically appropriate.

✔Explains how NHS fit notes and private medical certificates differ
✔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

Doctor, nurse, occupational therapist, physiotherapist, or pharmacist, normally through the NHS

When required

An employer can ask for one once an absence runs beyond 7 days in a row

Cost

Free when issued on the NHS

Used for

Statutory Sick Pay, longer absence, DWP benefit claims

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, each at the recipient’s discretion

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	Doctor, nurse, occupational therapist, physiotherapist, or pharmacist, under the 2022 medical evidence regulations	Any GMC-registered doctor (private or online)
Cost	Free when issued on the NHS	Fee-based, typically £30 to £50
Absence duration	An employer can only ask for one after more than 7 days in a row, including non-working days	Any duration, including under 7 days
Valid for SSP	Yes, the evidence an employer can ask for once an absence passes 7 days in a row	Not a fit note. GOV.UK tells employers that if they agree, the employee can give another appropriate form of evidence instead. It cannot be used for a DWP benefit claim
Valid for DWP benefits	Yes (ESA, Universal Credit)	No
Employer acceptance	The evidence an employer is entitled to ask for after more than 7 days in a row	Accepted only where the employer agrees, under their own sickness absence policy
University / insurance	Not usually required for these purposes	Commonly requested by universities and insurers, subject to each one’s own policy
Can be backdated	Can cover an earlier period, at the issuing clinician’s 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

An NHS fit note is what your employer can ask for at this point. It is free from your GP or another registered healthcare professional, and it is the usual evidence for a Statutory Sick Pay claim.

Off for 7 days or fewer

You can self-certify. GOV.UK’s Statutory Sick Pay guidance tells employers they can only ask for a fit note if the employee is off work for more than 7 days in a row, so no fit note is needed here. An employer may still ask for evidence under their own absence policy, and a private medical certificate from a GMC-registered doctor is one thing they can choose to accept.

University, insurers, or cancellations

For student evidence, travel insurance claims, gym cancellations, or event refunds, a private medical certificate is usually the document asked for. An NHS fit note is built around workplace absence and is not normally used for these purposes. Each organisation sets its own evidence policy, so check theirs first.

When Private Is the Only Option

Situations Where a Private Medical Certificate Is the Right Choice

There are common circumstances where an NHS fit note is either not available or not the right document, and a private medical certificate from a GMC-registered doctor is worth considering.

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 one option. An NHS practice is not required to issue a fit note for an absence of seven days or fewer, and may decline to. Whether the certificate satisfies your employer is for your employer to decide.

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 usually the document these organisations ask for. Each sets its own policy, so confirm what they need before paying for anything.

Validity & Acceptance

Are Private Medical Certificates Accepted by Employers?

A private medical certificate is written by a doctor bound by the same professional and regulatory obligations as one working in the NHS, under the General Medical Council’s Good Medical Practice framework. What differs is not the doctor’s standing but the document. A private certificate is not an NHS fit note, and it does not take a fit note’s place in the Statutory Sick Pay and benefits system.

Many UK employers will take a private medical certificate for short-term absences and early evidence requests, but none are obliged to. GOV.UK’s Statutory Sick Pay guidance for employers states that if the employer agrees, the employee can give another appropriate form of evidence instead of a fit note. Acceptance therefore rests with the employer, so check the sickness absence policy before paying for a certificate.

A private medical certificate is professionally credible, and stands the best chance of being accepted, 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: a fit note must come from one of the five professions authorised under the 2022 medical evidence regulations, and MedicalCert does not issue fit notes

›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 fit note, officially a Statement of Fitness for Work and often called a sick note or Med3, is issued free on the NHS by a doctor, nurse, occupational therapist, pharmacist, or physiotherapist. It is the evidence an employer can ask for once an absence runs beyond seven days in a row, and it is what the DWP works from for benefit claims such as 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 are written by a registered clinician, but they are different documents. A private certificate is not a fit note and does not replace one for Statutory Sick Pay or benefit purposes. MedicalCert provides private medical certificates and does not issue NHS fit notes.

Can a private sick note be used for Statutory Sick Pay?

Only if your employer agrees to accept it. A private certificate is not a fit note. GOV.UK’s Statutory Sick Pay guidance tells employers they can only ask for a fit note if the employee is off work for more than 7 days in a row, and that if they agree, the employee can give another appropriate form of evidence instead of a fit note. So a private certificate can serve for Statutory Sick Pay purposes where the employer accepts it, never automatically. For absences of seven days or fewer no fit note is needed at all, and since 6 April 2026 Statutory Sick Pay is payable from the first qualifying day. Check your employer’s sickness absence policy before paying for a certificate.

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. GOV.UK’s Statutory Sick Pay guidance for employers states that if the employer agrees, the employee can give another appropriate form of evidence instead of a fit note. 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. MedicalCert certificates are subject to the same discretion, and acceptance is decided by your employer.

Is a private sick note from an online doctor valid?

A private sick note issued by a GMC-registered doctor following individual clinical review is a genuine clinical document, and carries the same professional standing as one issued in person. Whether it is accepted is a separate question, decided by whoever you give it to. 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. MedicalCert issues private medical certificates this way, with every application reviewed individually by a GMC-registered UK doctor.

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. A GP practice can charge a private fee for a letter that sits outside its NHS contract, such as one covering an absence of seven days or fewer, and the practice sets that fee itself. 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?

Most UK universities will consider a private medical certificate as evidence for extenuating circumstances applications, deadline extensions, and assessment deferrals. An NHS fit note is designed for workplace absence and is not usually what a university asks for. Each university sets its own extenuating circumstances policy, and some specify a form or wording of their own, so read theirs before applying.

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. GOV.UK’s Statutory Sick Pay guidance for employers puts it as: you can only ask for a fit note if your employee is off work for more than 7 days in a row, including non-working days. Statutory Sick Pay has its own eligibility conditions on top of this.

Sources

Sources & References

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

GOV.UK, Statutory Sick Pay: employer guide, notice and fit notes

States that an employer can only ask for a fit note after more than 7 days in a row, and that if the employer agrees the employee can give another appropriate form of evidence instead.

gov.uk/employers-sick-pay/notice-and-fit-notes

Acas, Fit notes and proof of sickness

Advisory guidance on self-certification for absences of 7 calendar days or fewer, and on when an employer should ask for a fit note.

acas.org.uk/fit-notes-and-proof-of-sickness

DWP, Who can issue fit notes

Sets out the five professions able to certify fit notes under the 2022 medical evidence regulations, and confirms that alternative evidence can be given for Statutory Sick Pay where the employer is content.

gov.uk/government/publications/who-can-issue-fit-notes-guidance-for-healthcare-professionals-and-their-employers

Social Security Contributions and Benefits Act 1992 (Part XI)

The primary legislation establishing Statutory Sick Pay, as reformed by the Employment Rights Act 2025, with the waiting days removed from 6 April 2026.

legislation.gov.uk

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

Reviewed by Dr Maria Knobel

Medical Director, MedicalCert · GMC 7495073 · Last updated: 2 September 2026

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