Emma from the finance team asked me last Tuesday why nobody had warned her that "covering for Priya" during her four weeks in Portugal actually meant running two ledgers, fielding Priya's supplier calls, and still hitting her own month-end deadline. Nobody had warned her because nobody ever does. The request usually arrives as a five-minute chat by the coffee machine — "you'll just keep an eye on things while she's out" — and by week three you're doing a second job for free, with no meeting, no email, and no acknowledgement that anything unusual happened at all.
Why cover work has a habit of becoming permanent
The person asking you to cover almost never intends for it to expand the way it does. A manager under pressure to keep a team of six looking like a team of six, even when one person is on the beach, will quietly redistribute tasks in the path of least resistance — which is usually whoever answered "sure, no problem" the fastest the last time this happened. Three summers of that pattern, and you've become the informal backup for every role in the department, without a title, a pay rise, or so much as a line in your appraisal that reflects it. Priya's manager didn't sit down and decide to underpay Emma for a month; the arrangement simply drifted there, one Tuesday coffee-machine chat at a time. That drift is the actual mechanism, and it's precisely why waiting for someone to notice and fix it on your behalf almost never works. The fix has to come from you, before the cover starts, not from a manager who is currently very glad the problem has quietly gone away.
The maths your manager isn't doing
A four-week absence covered informally by one colleague means, on paper, that person is now doing 125 per cent of a full-time role for a month — their own workload plus a meaningful share of someone else's — for the same salary they were on in June. Whether or not the maths gets acknowledged is entirely a matter of who raises it and when.
Ask for the number before you agree to anything, not after: how many hours a week is this realistically going to add, and what happens to your own deadlines during that period? If the honest answer is "your deliverables slip a bit, that's fine", get it in writing — an email confirming that your normal targets are paused counts as protection later, when someone asks in September why a project ran late. If the answer is "no, everything still needs to land on time", that's the moment to say the cover isn't free: a day in lieu, a one-off payment, or at minimum a formal note that you took on additional scope, dated and specific enough to matter at your next pay review.
What to say when the ask comes with no warning
The coffee-machine version of this conversation puts you at a disadvantage, because it's designed to get a fast yes before you've thought about the scope. Buy yourself the hour you need with something simple and entirely reasonable: "Happy to help — let me check what's actually on my plate this week before I confirm what I can take on." That single sentence turns an ambush into a negotiation, and nobody reasonable will push back on it.
- Ask what specifically needs covering — not "keep an eye on things", but the three or four concrete tasks that will actually land on your desk
- Ask who else is being asked to help, because "just you" and "the whole team's pitching in" are very different arrangements
- Ask what happens to your own deadlines, in writing if you can get it
Don't accept "we'll sort it out when she's back" as an answer to any of the three. That phrase is doing a lot of work to avoid a decision someone doesn't want to make in July.
When it's worth pushing back hard
Not every cover request deserves a negotiation — sometimes a genuinely light two-day gap is exactly that, and making a fuss over it costs you goodwill you'll want later.
Push back properly when the absence is four weeks or longer, when you've covered for the same person more than once this year, or when the role being covered sits a full grade above yours — that third one especially, because doing a manager's job for a month with no formal acting-up arrangement is the surest way to end up doing it permanently for nothing. ACAS guidance on temporary cover is clear that additional responsibility should be reflected in either pay or a documented time-limited arrangement, and while most UK employers won't offer that unprompted, almost none will refuse it outright once you've actually asked. The awkward part isn't the request — it's screwing up the courage to make it before the cover period starts, while you still have leverage, rather than in September when the moment's passed and everyone's forgotten how hard July actually was.
The handover document nobody writes until it's too late
Most cover chaos traces back to a handover that never happened, or happened as a rushed voice note sent from the taxi to the airport. A proper handover takes maybe forty-five minutes to write and saves the covering colleague hours of guesswork every single week of the absence — which supplier calls back on which day, which client needs a "yes" and which one needs a "let me check", where the half-finished spreadsheet actually lives. Priya's handover, as it turned out, was three lines in a Slack message sent at 6am on the day she flew out, and Emma spent the first week of the cover reverse-engineering decisions Priya had already made but never written down anywhere.
If you're the one going on leave, block time for this properly rather than treating it as an afterthought squeezed between packing and the airport taxi. List the recurring tasks with their deadlines, the three people most likely to email asking for something, and the one or two decisions that can simply wait until you're back — spelling that last part out explicitly gives your cover permission to say "this can wait" instead of guessing wrong and either over-committing or under-delivering on your behalf. If you're the one covering and no handover exists, ask for one before the person leaves, not during their first week away when they're unreachable on a beach in the Algarve.
Why the same three people always seem to get asked
Look around most teams and the covering falls on a predictable shortlist — usually whoever doesn't have young children needing the school run, whoever's known for being easy-going, and whoever said yes without complaint the last time. That pattern compounds fast: the same three or four people quietly absorb every gap in the rota, year after year, while colleagues with a toddler at home or a standing excuse are never even asked. It isn't malicious, most of the time — it's a manager taking the path that causes the least friction today, with zero regard for who's already stretched thin from doing this every summer since 2022.
If you recognise yourself on that shortlist, the fix isn't to start saying no to everything — that just makes you the person who "used to be reliable". It's to make the pattern visible: mention, calmly and without drama, that you covered for two colleagues last summer and one this spring, and ask whether the rota could rotate a bit wider this time. Most managers haven't actually counted; once the number is in front of them, spreading the load usually isn't a hard sell. Flag it in the same conversation where you agree to cover, not three weeks in when the pattern's already obvious to everyone but your manager: "Happy to help — can we also look at spreading next summer's cover a bit wider, since I've done this twice already this year?" Said once, calmly, it reads as constructive rather than a complaint, and it's usually the only nudge a manager needs to actually open the rota up to people who've been quietly overlooked.
The long game: what good cover looks like on your annual review
Keep a running note — a single line in a phone app is enough — every time you cover someone else's work, with the dates and the specific tasks involved.
By December, that note is the difference between "I helped out a bit over summer" and "I ran two client accounts single-handedly for six weeks in July and August, on top of my own targets." The second version is promotion-case material; the first gets nodded at and forgotten by the time bonus decisions get made. Statutory annual leave in the UK sits at 5.6 weeks a year including bank holidays, and someone is always on it somewhere in the building between June and September — which means the informal-cover problem isn't a one-off summer inconvenience, it's a structural gap that keeps recurring every year until somebody with the standing to fix it actually does. Until that happens, the running note is yours to keep, and it's worth more at review time than any amount of quietly getting on with it ever was.
Emma got her day in lieu, in the end — three weeks after Priya was back, and only after she asked twice.