Pet insurance excess explained: what it is, how to choose

The excess is one of two numbers you actively choose at quote time (the other being the vet fee limit). It’s also one of the most misunderstood. This guide explains how UK pet insurance excesses actually work, the co-payment trap, and how to pick a setup that doesn’t catch you out.

What the excess is

The excess is the fixed amount you pay per condition, per policy year, before the insurer contributes anything. Common UK excesses are £75, £100, £150, and £200, with some insurers offering £250 or £300 for the cheapest tiers.

Three things to be clear about:

Per condition, not per claim. If your dog is treated for a skin allergy and you submit three separate claims in the same policy year, you pay the excess once. The next two claims for the same condition are paid in full (subject to the vet fee limit).

Per policy year, not per condition lifetime. A chronic condition that runs for ten years triggers the excess ten times, once at each renewal where it generates new bills.

Per condition, not per pet. If your dog has both a skin allergy and an unrelated cruciate rupture in the same year, you pay two excesses, one for each condition.

The co-payment trap

Here is where it gets expensive. Most UK pet insurers automatically introduce a co-payment when your pet reaches a defined age. Typical thresholds:

• 8 years old for dogs
• 10 years old for cats

The co-payment is a percentage of each bill (usually 10%, 15%, or 20%) that you pay on top of the excess. So a £6,000 cruciate repair on a 10-year-old dog with a £150 excess and 20% co-payment looks like this:

Item	Amount
Bill total	£6,000
Excess	£150
Remaining after excess	£5,850
20% co-payment	£1,170
Insurer pays	£4,680
You pay	£1,320

That £1,320 is a real number that lands in your bank statement. It is exactly the kind of bill that derails the “I’m insured, so I’m covered” assumption.

Excess vs co-payment vs premium

The premium calculation is roughly: insurer’s expected payouts minus the bit you absorb (excess and co-payment), with margin and admin on top. So the relationships are predictable:

• Higher excess: lower premium, more pain at claim time
• Higher co-payment: lower premium, much more pain on big bills
• Both together: notably lower premium, very large potential out-of-pocket exposure

For the same hypothetical Cocker Spaniel in SE15 we used in our cost guide, here is roughly how the same lifetime policy prices out at different excess and co-pay settings:

Excess	Co-payment	Approx monthly premium
£75	None	£42
£100	None	£36
£150	None	£33
£200	None	£30
£150	10%	£25
£200	20%	£19

The £15 to £20 a month gap between the cleanest setup (£75 excess, no co-pay) and the most painful (£200 + 20%) looks attractive on paper. Run a £6,000 surgical bill through both and the gap evaporates: the cheaper policy hands you back roughly £1,500 of out-of-pocket cost the day it matters.

How to choose an excess that doesn’t bite you

We work through this with three guard-rails:

1. Pick an excess you would happily pay tomorrow

If £200 makes you flinch, don’t pick £200. The excess is paid every claim year for every new condition. If a £200 hit on top of stressful vet news would push you towards “let’s just see if it gets better on its own”, choose lower.

2. Avoid co-payments under 8 if you can

Some budget brands now apply co-payments from age 6 or even policy start. This is genuinely poor product design dressed up as low premium. Insurers in our best UK picks shortlist generally either avoid co-payments entirely (ManyPets, Napo) or only introduce them at age 8 or older, with an opt-out at quote time.

3. Re-run the numbers at renewal each year

The right excess for a 2-year-old dog is rarely the right excess for a 10-year-old dog. As your pet ages, premiums climb sharply. Many insurers will let you adjust excess at renewal, which can be the difference between an affordable premium and a renewal that pushes you into changing insurer (and thereby losing cover for any chronic condition).

What about voluntary excess on top of compulsory excess?

A small number of UK insurers separate compulsory excess (which they set, typically £75 to £100) from voluntary excess (which you can stack on top to reduce premium). The arithmetic is the same: you are taking on more risk in exchange for a lower monthly cost.

The math only really works in your favour if you have low risk appetite for high premium movement and high risk tolerance for occasional large hits. For most owners, simpler is better: pick the excess you’d happily pay, no co-payment if you can avoid it, and don’t try to optimise the premium down by shifting risk back onto yourself.

Summary

The excess is per condition, per policy year, not per claim. The co-payment kicks in automatically at age 8 for most dog policies and 10 for most cat policies. Together they can transfer a meaningful share of the bill back to you at exactly the moment you don’t want to think about it.

For our current view of which UK insurers handle excess and co-payment most fairly, especially for older pets, see the best UK pet insurance picks for 2026 and the older dogs shortlist.