Sick During Annual Leave: Can Employees Reclaim Their Holiday?

Picture this: one of your team books two weeks off in July. Three days into their holiday they come down with food poisoning and spend the rest of the trip in bed. When they return to work, they ask to have those sick days reclassified as sick leave and their annual leave allowance restored.

Your first instinct might be to say no. They were off work either way, so what difference does it make? But under UK and European law, the employee almost certainly has the right to reclaim those lost holiday days. This is sometimes called the "sickness-to-holiday flip," and it is one of the most frustrating areas of leave management for HR teams and small business owners alike.

The Short Answer

Yes. If an employee falls ill during a period of pre-booked annual leave, they can ask for those sick days to be treated as sick leave instead of holiday. The employer must then restore the annual leave days so the employee can take them at a later date.

This applies to the core 4 weeks (20 days) of statutory annual leave derived from the EU Working Time Directive and retained in UK law. It does not automatically apply to any additional contractual holiday above the statutory minimum, unless the employment contract says otherwise.

Where Does This Right Come From?

EU Working Time Directive (2003/88/EC)

The right originates from the principle that annual leave and sick leave serve two fundamentally different purposes. Annual leave exists to allow workers to rest and enjoy leisure time. Sick leave exists because the worker is incapacitated. The European Court of Justice (ECJ) has consistently held that these two purposes cannot overlap: a worker who is sick is not resting, and therefore they are not receiving the benefit that annual leave is designed to provide.

The Key Case: Pereda v Madrid Movilidad SA (2009)

The landmark ruling came from the ECJ in Pereda v Madrid Movilidad SA (Case C-277/08, 2009). Mr Pereda was scheduled to take annual leave but fell ill before the leave began. His employer refused to let him reschedule. The ECJ ruled that:

• A worker who becomes sick during annual leave has the right to take the missed holiday days at a later date.
• The purpose of annual leave (rest and leisure) is different from the purpose of sick leave (recovery from illness), and one cannot substitute for the other.
• The rescheduled leave does not have to be taken immediately after the end of the sick leave period. It can be taken later in the leave year or carried over if necessary.

UK Law: Working Time Regulations 1998

The Working Time Regulations 1998 implement the EU Working Time Directive in the UK. Although the regulations do not contain an explicit provision about sickness during annual leave, UK courts and tribunals apply the Pereda principle. The right was retained in UK law after Brexit as part of the body of retained EU case law. For a broader overview of how these regulations work, see our UK employment law guide.

How It Works in Practice

1. The Employee Must Notify You

The employee should inform their employer as soon as reasonably possible that they are ill during their annual leave. Your sickness absence policy should set out how and when they need to do this. Many employers require notification within 24 hours, using the same reporting procedure as for normal sick leave (for example, a phone call to their line manager).

2. Medical Evidence May Be Required

Employers can require medical evidence to support the claim. For absences of seven days or fewer, a self-certification form is standard. For absences lasting more than seven calendar days, a fit note from a doctor is required, just as it would be for any other period of sickness. If the employee was ill abroad, a medical certificate from a local doctor in the country they were visiting is acceptable.

3. The Holiday Days Are Restored

Once the employer accepts that the employee was genuinely sick, the relevant holiday days are added back to their annual leave balance. The employee can then request to take those days at a later date, subject to the normal booking and approval process.

4. Sick Pay Rules Apply

For the days reclassified as sick leave, the employee receives whatever sick pay they would normally be entitled to, whether that is Statutory Sick Pay (SSP) or a more generous contractual sick pay scheme. This means they may actually receive less pay for those days than they would have received as holiday pay, depending on the employer's sick pay arrangements.

What About the Additional 1.6 Weeks?

UK workers are entitled to 5.6 weeks (28 days for full-time) of annual leave. This is split into two components:

• 4 weeks (20 days) from the EU Working Time Directive (now retained in UK law).
• 1.6 weeks (8 days) added by the UK Working Time Regulations as a top-up.

The Pereda ruling applies to the core 4 weeks. The additional 1.6 weeks are governed purely by UK domestic law, and the position is less clear. There is no explicit right to reclaim the additional days, and it has not been tested definitively in UK courts. In practice, most employers apply the same rule to the full 5.6 weeks for simplicity and to avoid disputes, but they are not strictly required to do so.

If your employment contracts offer leave above the 28-day statutory minimum, whether the sickness-to-holiday flip applies to those extra days depends entirely on the wording of your contract.

Why This Drives HR Managers Crazy

On paper, the rule makes perfect legal sense. Annual leave is for rest. Sick leave is for illness. They serve different purposes and should not overlap. In practice, though, it creates real headaches:

Staffing Gaps

The employee was already scheduled to be absent. The team adjusted. Now the employee wants to take those same days again at a different time, meaning the team has to absorb a second absence for the same person.

Verification Difficulties

How do you verify that someone was genuinely ill during a holiday in Tenerife? If the absence was short (a day or two), the employee may self-certify, and the employer has limited ability to challenge it. This leads to concerns about abuse, even if most claims are genuine.

Administrative Burden

Recalculating leave balances, adjusting payroll from holiday pay to sick pay, processing a new leave request for the rescheduled days, and keeping clear records of all of it adds time and complexity, especially for smaller businesses without dedicated HR software.

End-of-Year Pressure

If the sickness happens late in the leave year, the employee may need to carry over the reclaimed days into the next year. The carry-over rules for the core 4 weeks allow this when sickness prevents the employee from taking their leave, but it still means managing a larger leave balance in the following year.

Can Employers Push Back?

Not really. If the employee provides adequate medical evidence and follows the notification procedure, the employer is legally obliged to reclassify the days and restore the annual leave. Refusing to do so would amount to denying the employee their statutory holiday entitlement, which could lead to a tribunal claim under the Working Time Regulations.

However, employers do have some reasonable controls:

• Require prompt notification. The employee must report the sickness as soon as possible, using the same procedure they would follow for a normal sick day.
• Require medical evidence. Self-certification for short absences, a fit note for longer ones. A foreign medical certificate is acceptable for illness abroad.
• Apply the normal booking process to rescheduled leave. The employee does not get an automatic right to take the reclaimed days on dates of their choosing. They must request the new dates through the usual leave request process, and the employer can refuse on business grounds (provided they allow the employee to take the leave at some point before the end of the carry-over period).

What About Sickness Before the Holiday Starts?

The same principle applies. If an employee falls ill before their pre-booked holiday begins and is still sick when the leave period starts, they can choose to cancel the annual leave and take it as sick leave instead. The Pereda ruling covers both scenarios: becoming sick before the holiday and becoming sick during it.

In this case, the employee should notify the employer before the leave starts (or as soon as possible) and provide the usual medical evidence.

Practical Tips for Employers

1. Have a Clear Policy

Include a specific section in your sickness absence policy that covers illness during annual leave. Set out the notification requirements, evidence needed, and the process for rescheduling the reclaimed days. Staff should know exactly what to do before they go on holiday.

2. Specify Notification Deadlines

Require employees to notify you within a reasonable timeframe (for example, within 24 hours of falling ill, or on the first day of sickness). This prevents employees from retrospectively claiming they were ill after the holiday is over.

3. Require Evidence for All Claims

Even for short absences, require at minimum a self-certification form completed promptly after the employee returns to work. For longer absences, a fit note (from a UK or overseas doctor) should be mandatory.

4. Track Everything

Keep accurate records of original leave bookings, sickness notifications, medical evidence received, leave balance adjustments, and rescheduled leave requests. Good record-keeping protects the business if a dispute arises.

5. Apply Rules Consistently

Treat all claims the same way, regardless of the employee's seniority or your personal view of whether they were "really" ill. Inconsistent treatment can lead to grievances and, in some cases, discrimination claims.

A Worked Example

Key Legislation and Case Law

Further Reading

• UK Employment Law: Staff Leave, Sick Pay, and Holiday Rights
• UK Holiday Entitlement Guide 2026
• The Bradford Factor Explained
• Leaver Holiday Pay Calculator

Disclaimer: This guide is for general information only and does not constitute legal advice. Employment law is subject to change. For specific situations, consult a qualified employment lawyer or ACAS (the Advisory, Conciliation and Arbitration Service).