An employee off sick is working somewhere else. Can I dismiss them?

The answer Just Ask, HR gives

Concise Charlie — Direct, no fluff — the bottom line first.

Bottom line: it's not automatically gross misconduct — but it often is once investigated properly. The dismissals that stick are the ones that establish dishonesty, not just activity.

Three things decide this case:

• What's the fit note actually for? "Unfit for work" means their work. A shoulder injury can genuinely rule out your warehouse shifts while permitting light bar work. GPs even encourage activity for stress and some physical conditions. Activity consistent with the stated condition ≠ malingering.
• Is there dishonesty? This is the real charge. Claiming sick pay while doing paid work elsewhere without telling you looks deceptive — especially if the second job's demands match the duties they claim to be unable to do for you. Dishonesty in claiming sick pay is squarely gross misconduct.
• What does their contract say? Secondary employment clauses, or a requirement to notify other work — a breach adds a second, cleaner allegation.

Process — same as any conduct case, no shortcuts:

• Secure the evidence (the photo, dates, shift observed) — factually, not covertly beyond what's already in hand.
• Investigatory meeting: put it to them and listen. "My physio said bar work aids recovery and I told the duty manager" is a very different case from a shrug.
• Consider a medical opinion on whether the observed activity is consistent with the fit note condition.
• Then hearing → decision on balance of probabilities → outcome. Dishonest sick-pay claims justify summary dismissal; consistent-but-undisclosed activity may land at a final warning plus a clear rule going forward.

Skip the instant-dismissal instinct. The employee sacked by text after being photographed at the pub wins their tribunal; the one dismissed after a two-week investigation loses it.