Whether you can work another job while on sick leave depends on your contract and why you are off sick. In the UK, working while on sick leave is not automatically illegal — but it carries significant risks including dismissal for gross misconduct, benefit fraud allegations, and breach of the implied duty of mutual trust and confidence.
Key Takeaways
- Working for another employer while signed off sick from your main job is likely to be a breach of contract and gross misconduct if you claimed you were too unwell to work your normal role.
- If you are on long-term sick leave and your contract allows other employment, you may be able to take on alternative work — but only within the limits of your medical fitness.
- SSP fraud occurs if you claim Statutory Sick Pay while working — even one day of work during a period you are signed off can trigger an investigation by HMRC.
- Some contracts contain an express clause prohibiting other employment during sick leave — check yours before taking any work.
- If you are considering other work as part of a phased return or rehabilitation plan, discuss it with your employer first.
When It Is Clearly a Problem
The most common and risky scenario: you are signed off sick from your main job, claiming you cannot perform your duties due to illness or injury, and you take work with another employer during that period. This is problematic for several reasons:
It contradicts your medical certification. Your fit note states you are “not fit for work” or “may be fit for work taking into account the following advice.” If you are well enough to work elsewhere, you should not be signed off from your main job.
It breaches the implied duty of trust and confidence. Every UK employment contract contains an implied term of mutual trust and confidence. Working for someone else while signed off sick usually destroys that trust. If discovered, it is almost always treated as gross misconduct resulting in summary dismissal.
It may constitute SSP fraud. Claiming Statutory Sick Pay (SSP) from your employer while working elsewhere is benefit fraud. HMRC can investigate and require repayment, and your employer can dismiss you. The maximum penalty for benefit fraud can include prosecution in serious cases.
When It May Be Acceptable
There are limited circumstances where working while on sick leave is not automatically a breach:
Long-term sick leave with company knowledge. Some employees on extended sick leave agree with their employer to take on limited alternative work as part of a rehabilitation plan or phased return. This should always be agreed in advance and confirmed in writing.
Self-employed contracts. If you are working under a separate self-employed contract in a different field, and your main employment contract does not prohibit it, the risk is lower — but you must still be truthful about your fitness for work.
Voluntary or charitable work. Some employers allow unpaid voluntary work during sick leave, particularly for mental health recovery. Check your contract and discuss with your employer first.
What the Contract Says
Your employment contract is the starting point. Many contracts include one or more of these clauses:
| Clause type | What it means |
|---|---|
| “No other employment without prior written consent” | You cannot take any other work without permission |
| “During any period of sickness absence, the employee shall not engage in any other paid or unpaid work” | Expressly prohibits any work during sick leave |
| “The employee shall devote their whole time and attention to their duties” | Indirectly prohibits other employment — ambiguous, but often enforced |
If your contract is silent on other employment during sick leave, the implied duty of mutual trust and confidence still applies. Working for someone else while too sick to work for your employer would likely be a breach.
What Happens If You Are Caught?
Employers typically treat working while on sick leave as gross misconduct, leading to summary dismissal without notice or pay in lieu of notice. Some employers also pursue recovery of SSP paid during the period when you were working elsewhere. In rare cases, employers have brought civil claims for breach of contract.
If the employer discovers the other work through social media, a tip-off, or a private investigator, the evidence is usually straightforward — photographs, social media posts, or invoices proving you were working elsewhere during your sick leave period.
FAQ
Can I work from home for another company while on sick leave?
Only if your main employer is aware and has given permission. Working from home does not change the legal position — if you are too unwell to work for your employer, you are too unwell to work for anyone else, unless specifically agreed.
What if the other job is completely different (e.g. light admin work while off with a physical injury)?
This is less clear-cut but still risky. If your fit note says you are fit for “work that does not involve heavy lifting,” and you take an admin role elsewhere, the risk is lower — but you still need your employer’s permission if your contract requires it.
What if I work for a family member’s business while on sick leave?
The same rules apply. If you are well enough to help at a family business, you should be well enough to perform adjusted duties at your main employer.
Can self-employment continue during sick leave from an employed role?
It depends on your contract and the nature of the self-employment. If your self-employment is passive (rental income, investments) it is usually fine. If it involves active work, check your contract’s other employment clause and discuss it with your employer.
What should I do if I want to start another job while on sick leave?
First, check your contract. Second, speak to your employer about whether a phased return or adjusted duties at your current role would be possible. Third, seek legal advice before taking any paid work during a period of certified sickness absence.