Understanding Fit Notes and What Your GP Can and Cannot Say

Why this matters

Managing a chronic or fluctuating condition alongside work is one of the more practically complex aspects of living with long-term illness. Understanding what a fit note can and cannot do, and what rights come with it, makes it easier to navigate absence, adjustments, and conversations with employers without unnecessary uncertainty.

When a fit note is needed

For the first seven days of any absence, self-certification is sufficient; there is no need to involve a GP. From day eight onwards, employers can require a fit note. GPs can backdate a fit note if they assessed the patient during the illness period but cannot backdate to a period before they were seen.

What GPs can and cannot write

A fit note includes a fitness assessment, the condition or symptom description, and a duration. On the fitness assessment, a GP can certify either that someone isn’t fit for work at all or that they may be fit with adjustments, such as a phased return, amended duties, altered hours, or workplace adaptations.

The diagnosis can be specific or deliberately vague for privacy, for example, "musculoskeletal problem" rather than a named condition. GPs cannot issue a fit note without carrying out a clinical assessment, cannot make them indefinite, and cannot include detailed medical information that an employer isn’t entitled to.

Common Scenarios

• Short-term illness or flare. The GP assesses temporary unfitness and issues a fit note for the expected recovery period. If recovery takes longer, returning for an extension is straightforward
• Chronic conditions with variable fitness. Fit notes can cover periods of active disease, or "may be fit with adjustments" wording can support flexible working during less severe periods. Intermittent fit notes are also possible for conditions that fluctuate
• Mental health conditions. Depression, anxiety, and stress-related illness are all valid reasons for a fit note. GPs can use vague wording such as "stress-related illness" if a specific diagnosis on record isn’t preferred

Your rights

Employers must accept a valid fit note as evidence of unfitness and cannot require someone to work while one is in place. They also cannot dismiss an employee immediately for sickness absence. If the fit note states "may be fit with adjustments," the employer must consider whether those adjustments are practicable. If they aren’t, the employee is treated as not fit for work and entitled to statutory sick pay.

Chronic conditions that substantially affect daily activities and are likely to last twelve months or more often qualify as disabilities under the Equality Act 2010, which places additional requirements on employers to make reasonable adjustments.

What you could do

• Keep copies of all fit notes, including dates and reasons: these are supporting evidence for benefits applications, including ESA, PIP, and Universal Credit
• If a GP declines to issue a fit note, explain the functional impact clearly rather than focusing on symptoms alone. A second opinion from another GP in the practice is also an option, or seek an Occupational Health assessment through the employer
• If a fit note states adjustments are needed, ask the employer to put the agreed response in writing

Fit notes are a practical tool for protecting health and employment at the same time. Knowing how they work removes much of the uncertainty that surrounds them.

This article is for general information purposes only and doesn’t constitute legal, financial or benefits advice. For advice specific to your situation, please speak to a qualified professional or contact an organisation such as Citizens Advice, who may be able to assist you further.

References:

‘Equality Act 2010’ (2010) https://www.legislation.gov.uk/ukpga/2010/15/contents

‘Fit notes issued by GP practices: guide’ (2025) https://digital.nhs.uk/data-and-information/publications/statistical/fit-notes-issued-by-gp-practices/guide

‘Fit note: guidance for employers and line managers (2013) https://www.gov.uk/government/publications/fit-note-guidance-for-employers-and-line-managers