Travel insurance is one of those purchases most of us make in a hurry: a few clicks at checkout, a policy PDF nobody opens, and a vague sense that we're covered for whatever happens. Then a claim gets rejected for a reason that was in the terms all along. Knowing which parts of a policy do the heavy lifting, and which are thinner than they sound, makes the difference between a payout and an expensive lesson.

Medical cover: the part that earns its keep

Emergency medical treatment is the reason travel insurance exists. A fractured ankle in the Alps, a chest infection in Thailand, an appendix that decides to misbehave in Vietnam — treatment, an air ambulance or a medically supervised flight home can reach sums that make the cost of the trip look trivial.

Look for three things. First, that emergency medical expenses and repatriation are covered to a limit you're comfortable with, and that repatriation means getting you home to the UK rather than to the nearest hospital. Second, the excess, which is often higher on medical claims than on baggage ones. Third, the procedure: most insurers insist you ring their 24-hour assistance line before non-urgent treatment, and some will only pay for hospitals they've approved. Calling first feels like fuss when you're in pain, but skipping it is a common reason claims get trimmed.

The UK Global Health Insurance Card, and the older EHIC, give you access to necessary state healthcare in many European countries on the same terms as a local resident. Useful, but it isn't insurance. It won't cover a flight home, a private clinic, lost luggage or a cancelled trip.

Cancellation and curtailment: where arguments start

Cancellation cover reimburses prepaid, non-refundable costs if you have to pull out for a reason the policy lists: illness, a bereavement, jury service, your home being flooded or burgled. Curtailment covers coming home early or missing part of a trip.

Two things to watch. The list of reasons is closed — changing your mind, a busy spell at work or a falling-out with your travelling companion won't qualify. And the cover usually applies to you plus close relatives whose illness forces you to cancel, so check how "close relative" is defined if you're travelling with extended family.

Set the cancellation limit against your real, total, prepaid spend: flights, accommodation, tours, non-refundable car hire. Buy the policy at the same time as you book the first element, not the week before departure. Cancellation cover only protects money you'd already committed to.

Baggage, gadgets and the receipts nobody keeps

Baggage cover looks generous on the summary page and rather thinner in the detail. Per-item limits, a per-claim excess and depreciation on older kit all nibble at the payout. A laptop or camera might sit under a per-item cap below what it costs to replace.

Insurers want evidence: a receipt, a bank statement, a photo of the serial number. Before you pack, photograph your electronics and note the serial numbers somewhere you can reach from abroad. Report a theft to the local police quickly and get a written report — most policies ask for this, and without it a claim is hard to argue.

Check whether your home contents insurance already covers possessions away from home, and how much it would pay after its own excess. Duplicate cover is wasted money. Note too that items left unattended — in a car, on a sun lounger, in a checked bag — are commonly excluded.

Activities: the add-on that changes everything

A standard policy handles the gentle stuff: swimming, hired bikes, marked walking trails, the odd boat trip. Step up to anything with altitude, speed or a guide and the picture shifts.

• Winter sports: usually an add-on, with off-piste cover often excluded unless you're with a qualified guide.
• Water sports: jet skis, kite surfing and diving below a stated depth may need specific cover.
• Two wheels: motorcycling above a certain engine size, or riding without a licence and helmet, can sink a claim.
• Altitude: trekking above a set height is typically excluded as standard, so check the threshold before you book the trek.

Read the activity list, not just the front page, and match it to what you'll genuinely do. If it's one day of skiing in a fortnight of walking, an add-on for that window is often cheaper than a full winter sports upgrade.

Pre-existing conditions: the honesty clause

Most declined claims come back to this. If you've had treatment, taken regular medication, or been referred for tests in recent years — asthma, high blood pressure, a mental health condition, even a result you're still waiting on — it almost certainly needs declaring.

The insurer will then cover it for an extra premium, exclude that condition only, or decline the policy. What they won't do is pay a claim for something you didn't mention. Non-disclosure can invalidate the whole policy, not just the part relating to your condition.

Specialist insurers cover many conditions that mainstream ones won't, so a decline isn't the end of the road. Answer medical questions fully and honestly. This is general guidance rather than financial or medical advice — if you're unsure how to describe a condition, ring the insurer or a specialist broker and ask them to confirm their answer by email.

The small print that catches people out

• Alcohol. Claims linked to heavy drinking are routinely reduced or refused, and many policies exclude incidents where you were intoxicated.
• Stacked excesses. Check whether the excess is charged per person, per section or per claim — it matters for a family claiming together.
• Deadlines. Theft often has to be reported to police within a day or two, and claims submitted within a set period after you get home.
• Missed departures. Arriving too late because you cut it fine, or didn't check in on time, usually isn't covered.
• Strikes and airline failure. Not always included. If scheduled airline failure cover is offered, it's worth having.
• Reasonable care. Policies expect you to behave as though you were paying the bill yourself.

Buying cover you won't regret

1. Buy when you book the trip, so cancellation cover starts immediately.
2. Declare every medical condition, however minor it seems.
3. Set the cancellation limit above your total prepaid, non-refundable spend.
4. Match the activity cover to your actual itinerary.
5. Read the exclusions and the excess table before paying.
6. Save the emergency assistance number in your phone and on paper.

If something in the wording is unclear, ring and ask before you buy, not after something goes wrong. Ten minutes on the phone is cheaper than discovering, halfway through a claim, that the one thing you needed was the one thing excluded.

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