Fit notes and self-certification: proving sickness absence

The fit note is the piece of paper, usually now a PDF, that sits between you and your sick pay. The rules around it are simple once you know them, and employers get them wrong often enough that it is worth knowing them properly.

The first seven days: self-certification

For the first seven calendar days of sickness you do not need anything from a doctor. You self-certify: tell your employer you are unfit for work, usually on form SC2 or your employer's own form.

Two points that matter:

• Your employer cannot demand a doctor's note for the first seven days. If they insist on one, they are wrong, and a GP is entitled to charge for a letter covering that period because it is not an NHS service.
• Sick pay follows the same timeline. Statutory sick pay is payable from day one under the rules in force since 6 April 2026, so the first week is paid, not just excused.

After seven days: the fit note

From day eight you need a fit note, formally a Statement of Fitness for Work. Since July 2022 these can be issued not only by GPs but also by nurses, occupational therapists, pharmacists and physiotherapists, which has made getting one considerably easier.

A fit note says one of two things:

• Not fit for work. Straightforward: you are signed off for the stated period.
• May be fit for work. The clinician thinks you could return with support, and the note can suggest adjustments: phased return, altered hours, amended duties, workplace adaptations.

A "may be fit" note is not an instruction to your employer, but it is not nothing either. Your employer should discuss the suggested adjustments with you and make reasonable changes. If no adjustment is possible, the note effectively operates as "not fit" and you stay off. If your condition is a disability, the duty to make adjustments is a legal one under the Equality Act 2010. If your condition amounts to a disability, adjustments are a legal duty rather than a favour: our disability discrimination guide explains.

How fit notes and sick pay connect

Your employer can ask for evidence of sickness for SSP purposes, and the fit note is that evidence after the first week. Practical points:

• Keep the note in date. A gap between an expired note and a new one is a gap in evidence, and some employers use gaps to stop pay. Book the follow-up before the note runs out.
• Backdating is possible. Clinicians can backdate fit notes where clinically appropriate, so a gap is often fixable.
• Give it to your employer promptly. The note is your responsibility to pass on, usually as a photo or PDF.

When employers push back

The awkward cases:

• "We do not accept fit notes, you need to come in for a meeting." They can invite you to a welfare meeting, reasonably conducted, but they cannot override a fit note and compel you to work.
• Pressure to return early. An employer who leans on you to come back before the note expires is creating risk for themselves, particularly if your condition is a disability or the pressure becomes a grievance.
• Sick pay stopped despite a valid note. Ask why, in writing. If SSP is withheld, your employer must explain the decision and you can ask HMRC to rule on entitlement.
• Disciplinary action over absence. Absence covered by fit notes is genuine absence. Using it as a misconduct issue is exactly backwards, and if the absence is disability-related it may be discriminatory in itself.

The longer picture

If your absence is stretching beyond a few weeks, the questions move on from evidence to money and job security: what happens when SSP ends, how holiday keeps accruing, and what a fair capability process looks like. Those are covered in our guides to long-term sick pay and dismissal while on sick leave.

A fit note is evidence, and evidence is protection. Keep them current, keep copies, and if your employer starts treating yours as an inconvenience, that is the moment to get advice.