Can I dismiss an employee on long-term sick leave?

The answer Just Ask, HR gives

Detailed Dan — Structured and thorough — every step in order.

Yes — dismissal for long-term ill-health absence can be fair. It's a capability dismissal, and the law expects patience and process rather than an indefinite wait. Tribunals ask: did the employer act reasonably in treating the absence as sufficient reason, at the time they did? Here's what "reasonably" looks like:

1. Up-to-date medical evidence is non-negotiable. Commission an occupational health report asking specific questions: prognosis, likely return timescale, what adjustments would enable a return, permanence. A tribunal will not accept "we assumed".
2. Consult the employee throughout — regular, humane welfare meetings, not radio silence then a dismissal letter. Ask what they think would help. Their input shapes what's reasonable.
3. Exhaust the alternatives first: phased return, lighter duties, different role, later start times, homeworking. If the condition amounts to a disability under the Equality Act 2010 — after eight months, quite possibly — these become legally required reasonable adjustments, and you'll also need to justify the dismissal as proportionate (discrimination arising from disability, s.15).
4. Check for medical severance schemes — permanent health insurance or ill-health retirement under any pension scheme must be considered before dismissal; dismissing someone out of PHI cover is a classic (expensive) mistake.
5. Only then: a formal capability meeting with the medical evidence shared in advance, right to be accompanied, genuine consideration of their representations, notice paid, and a right of appeal.

The question a tribunal ultimately weighs is whether a reasonable employer of your size could be expected to wait longer. A 200-person firm can cover an absence a 6-person firm cannot — your size is legitimately part of the equation. Document the operational impact as you go.