How long can a UK employee be off sick before you can dismiss them?

It is one of the most stressful questions an SME owner can face. Someone has been off sick for weeks. Sometimes months. You feel a mixture of sympathy, frustration, and quiet panic about the work piling up. And the question that you cannot quite ask out loud starts to form: at what point can we actually let them go?

The honest answer is: there is no fixed period after which dismissal becomes automatically legal. UK law does not give you a magic number of weeks at which an absent employee becomes fair game. What it does give you is a process that, if followed properly, lets you dismiss on the grounds of ill-health capability with a defensible position at tribunal.

This guide walks you through that process. It is written for UK SMEs without an in-house HR team. By the end you will know exactly what you can do, what you must do, and when (if ever) dismissal becomes a realistic option.

The short version

You can dismiss for long-term sickness when:

1. You have followed a fair process (information-gathering, occupational health, consultation, reasonable adjustments).
2. You have a reasonable belief, based on medical evidence, that the employee will not be able to return to the role in a reasonable timeframe.
3. The business genuinely cannot wait any longer for that return.
4. You have considered redeployment and made it explicit in writing why redeployment was or was not possible.

How long is “a reasonable timeframe”? Tribunals have upheld dismissals after 6 months of continuous absence and overturned dismissals after 18 months where the process was flawed. The duration matters less than the process.

Step 1: Stay in touch from week one

The single most common reason long-term sickness cases go wrong at tribunal is that employers stop talking to the absent employee. They feel awkward. They worry about “harassing” someone who is unwell. So they retreat.

That retreat is the mistake. From day one of a sickness absence longer than two weeks, you need a documented stay-in-touch protocol. Weekly check-in calls or messages, light-touch, signed off by the employee. Document every interaction. Ask three things every time: how are you, what does the GP say about timing, is there anything we can do that would help.

Step 2: Trigger occupational health early

Most SMEs leave this far too late. A referral to occupational health (OH) should happen at the four-week mark, not the four-month mark. OH gives you a written, independent medical opinion on:

• What the underlying condition is (in broad terms, with appropriate confidentiality)
• When return to work is realistic
• What reasonable adjustments would help return
• Whether the role itself is sustainable for this person given the condition

That OH report is the foundation of every later step. Without it, you are guessing. With it, you have evidence-backed grounds for the decisions you make.

OH referrals are typically £200 to £400 per case. If you are on our Retained HR Support, we make the referral and handle the report interpretation. If not, your insurance broker can usually recommend an OH provider.

Step 3: Consider reasonable adjustments under the Equality Act

Long-term sickness almost always meets the Equality Act 2010 definition of disability (a physical or mental impairment lasting 12 months or more with substantial adverse effect on day-to-day activities). That triggers your duty to make reasonable adjustments.

Reasonable adjustments to consider, with OH input:

• Phased return (reduced hours building back up)
• Modified duties (removing the parts of the role that are not currently sustainable)
• Equipment, software, or workspace adjustments
• Working from home arrangements
• Time off for medical appointments treated as paid working time
• Mentoring or buddy support during return

You do not have to accept every adjustment. You have to consider them, document why you accepted or rejected each one, and act reasonably. The “reasonable” test for SMEs is different from the test for a 5,000-employer FTSE 100. Cost, disruption to other staff, and size of business are all relevant factors.

Step 4: The formal capability process

If after 3 to 6 months of absence (depending on the role and the medical picture) there is no clear return-to-work prospect, you move to a formal ill-health capability process. The process has three stages, each requiring a written invitation, a meeting, and a written outcome.

Stage 1: Initial capability meeting

Set out the situation. Review the OH report. Discuss the prognosis. Confirm the adjustments you have considered. Agree a clear, written timeline for review: typically 4 to 8 weeks. Document the meeting.

Stage 2: Review capability meeting

At the agreed review point, meet again. Has the situation moved? What has updated OH said? Are further adjustments possible? Agree a final review date. Make clear, in writing, that this is the final review and that dismissal is a possible outcome if return is not foreseeable.

Stage 3: Final capability meeting

At this final review, you make the decision. If the medical picture is clear, return is not foreseeable, no further adjustments are reasonable, and the business cannot wait, dismissal on the grounds of ill-health capability is a fair option. The employee is entitled to be accompanied by a colleague or trade union representative. The employee has the right to appeal in writing within a stated period (typically 7 working days).

Step 5: The dismissal decision

The dismissal letter must set out:

• The reason for dismissal (ill-health capability, the fair-reason category under the Employment Rights Act 1996 section 98)
• The medical evidence relied on
• The adjustments considered and why they were not enough
• The redeployment options considered and the outcome
• The notice period
• The right to appeal

Notice pay is required. SSP entitlement continues during notice if applicable. Pension and contractual benefits continue during notice. Any contractual sick-pay scheme should be paid in full.

The Employment Rights Act 2025 angle

The ERA 2025 changed the day-one rights landscape. Two specific points affect long-term sickness cases:

• SSP from day one with no Lower Earnings Limit. SSP is now payable from the first day of absence and applies to all earners. This affects budgeting more than process, but it does mean longer-term financial pressure on the business is different from what it was before April 2025.
• Day-one protection against unfair dismissal. The two-year qualifying period for unfair-dismissal protection is gone. Every employee, regardless of length of service, can bring an unfair-dismissal claim from day one. This makes following the proper ill-health capability process more important, not less, for short-tenure employees too.

When is dismissal the right call?

The threshold question is not “are we allowed to dismiss?” but “is dismissal the right business decision?”

Dismissal is usually the right call when:

• The medical evidence is clear and consistent that return to the specific role is not foreseeable
• You have run a proper process with documented adjustments and consultation
• The cover arrangements are unsustainable financially or operationally
• The employee has not engaged with OH or the capability process despite reasonable opportunities

Dismissal is usually not the right call when:

• OH says return is realistic within 1 to 2 months
• The employee has not yet had a fair chance to engage with adjustments
• You have skipped any of the formal capability stages
• The role has changed during the absence and you have not consulted on the changes

What it costs to get this wrong

The average ill-health unfair dismissal compensation award in 2024-25 was around £18,000. The maximum is now the lower of 52 weeks of gross pay or the statutory cap (set annually, currently around £115,000). Plus tribunal costs, plus legal fees, plus reputational damage in a small community where word travels.

The cost of running the process properly with HR support: typically £1,500 to £3,500 across the full timeline. The maths is straightforward.

What to do this week

If you currently have an employee on long-term sickness absence:

1. Audit your stay-in-touch records. If you have not been in regular contact, restart it this week with a polite, light-touch message.
2. If no OH referral has been made and the absence is past four weeks, make one now.
3. If you are past three months without a clear return picture, get HR support engaged before you take any further action.

If you are anywhere in this situation and want a 15-minute conversation with no obligation to figure out the right next step, book a call. We have run dozens of long-term sickness capability processes. Most of them ended in successful return to work. The few that ended in dismissal did so with no tribunal exposure.

Related Beagle HR services and tools you may find useful:

• Retained HR Support: phone-and-email advice, OH referrals included from your monthly hours.
• Bradford Factor Calculator: helps with the short-term frequent-absence pattern rather than long-term.
• Contracts & Policies: get your sickness absence policy and capability process documented before you need them.
• Which service is right for me?: 2-minute decision tree.