Understanding when an employee's illness becomes a disability is essential for employers — especially in high-pressure environments like GP surgeries, where staff wellbeing directly impacts patient care.

Under English law, the definition of disability is broader than many people realise. Misunderstanding it can lead to legal risk, particularly around absence management, performance concerns, and workplace adjustments.

The legal definition of disability

Under the Equality Act 2010, a person is considered disabled if they:

“Have a physical or mental impairment which has a substantial and long-term adverse effect on their ability to carry out normal day-to-day activities.”

Let’s break that down:

1. Physical or mental impairment
   This includes a wide range of conditions — such as depression, anxiety, cancer, diabetes, chronic pain, mobility issues, or neurological conditions.
   
   
2. Substantial effect
   The condition must make daily life more difficult — however the word ‘substantial’ is misleading. The Tribunals will agree that the effect is substantial where it is ‘more than trivial’. It’s a low bar.
   
   
3. Long-term
   The impairment must have lasted — or might well last — 12 months or more. Conditions that come and go (like multiple sclerosis or some mental health conditions) may still qualify if they have a recurring impact.
   
   
4. Normal day-to-day activities
   These include things like walking, sleeping, concentrating, lifting, communicating, and using a computer. It does not extend to specific work-related tasks.
   
   

Common misconceptions

• Not all illnesses are disabilities — a short-term illness like the flu wouldn’t normally qualify.
• But some conditions are automatically classed as disabilities, such as cancer, HIV, and multiple sclerosis, from the point of diagnosis — regardless of current symptoms.
• Mental health matters — depression, anxiety, and PTSD can be disabilities if they meet the above test.

Why it matters for employers

If an employee’s illness meets the legal definition of a disability, you have a duty to make reasonable adjustments to support them at work. This might include:

• Changing duties or shifts
• Providing assistive equipment
• Allowing additional time off or flexible hours
• Offering a phased return after long-term absence

Failing to make adjustments (and the duty is on the employer to make the adjustment proactively – not just in response to an employee’s request), or treating someone unfavourably because of their disability or something which arises in consequence of their disability, could lead to claims of disability discrimination. 

Not only are claims of disability discrimination complicated to defend, they can be expensive. An employee can claim uncapped compensation for financial losses and the way they have been made to feel. The final amount will depend on the circumstances of an individual case. 

What should employers do?

• Don’t try to “diagnose” — focus on the impact, not the label. If an employee reports a physical or mental condition which is impacting how they act and feel, it’s safest to assume there is a disability (without necessarily accepting it) and act accordingly. Just because someone has a disability, it does not mean you can’t deal with issues, but care needs to be taken.
• Get medical advice — through fit notes, GP reports, or occupational health assessments.
• Document discussions and adjustments made with the employee.
• Train managers to recognise when an illness may fall under the Equality Act.
• If taking disciplinary action, dealing with a grievance or dismissing, take prompt advice.

Specific Considerations for GP Practices

• CQC Expectations: The Care Quality Commission (CQC) expects practices to foster inclusive, well-led working environments. Demonstrating compliance with equality law is part of showing strong governance and leadership.
• NHS Contracts: Your contract requires compliance with all applicable employment and equality laws. Failure to manage disability issues properly could — in rare cases — raise concerns around wider contractual obligations, particularly if it affects staff morale, retention or care delivery.
• Data Protection: When handling fit notes, occupational health reports, or any medical information, ensure compliance with data protection regulations. Use a lawful basis for processing, and keep records secure and confidential.

GP surgeries deal with illness day in, day out but for Practice Managers and Partners, knowing when illness becomes a disability is crucial. It’s important to create a supportive, inclusive environment for your team whilst ensuring you handle HR issues sensitively and without falling foul of the Equality Act.

If you wish to discuss any employment law related questions, please contact Sarah Young in our Primary Care team.