Excess, co-insurance, and pre-existing conditions explained

Three terms that decide how much you pay — and whether a claim is covered at all — on typical UK pet insurance policies.

What is an excess?

The excess is the amount you agree to pay towards a claim before the insurer pays the rest (subject to limits and exclusions). It is similar in idea to a car insurance excess, though pet policies often apply it per condition, per year, or per claim — check which rule your policy uses.

A higher excess usually means a lower premium. That trade-off only helps if you can afford the excess when a bill arrives. For a £2,000 course of treatment and a £100 fixed excess (with no other deductions), you might pay £100 and the insurer the remainder of eligible costs. If several separate conditions arise in one year, you may pay an excess for each, depending on the wording.

Some policies also apply a higher excess once a pet reaches a certain age. Read renewal documents carefully; excesses can change even if the brand name on the paperwork stays the same.

What is co-insurance (or a percentage contribution)?

Co-insurance — sometimes called a voluntary or compulsory contribution — means you pay a percentage of the eligible claim as well as, or instead of focusing only on, a fixed excess. For example, after the fixed excess is taken off, you might still pay 20% of the remaining eligible costs.

This matters on large bills. On a £5,000 eligible claim with a £100 excess and 20% co-insurance on the balance, your share can be hundreds of pounds, not just the headline excess. Older pets’ policies often introduce or increase percentage contributions at renewal.

When you compare quotes, look at both the fixed excess and any co-insurance — not premium alone. A cheap monthly price with high contributions can leave you exposed when treatment is expensive.

How do they work together?

Insurers typically deduct the fixed excess first, then apply co-insurance to what is left of the eligible amount, then apply annual or per-condition limits. Non-covered items (for example some diets, grooming, or excluded procedures) stay your responsibility entirely.

Ask your insurer for a worked example using a sample invoice if the schedule is hard to follow. Understanding the arithmetic before you claim reduces nasty surprises — see also how to make a claim.

What is a pre-existing condition?

In plain terms, a pre-existing condition is an injury, illness, or set of clinical signs that existed — or showed symptoms — before your policy started, or during a waiting period at the start of cover. Most UK pet insurance will not cover treatment for those issues.

Important nuances:

• Symptoms, not just diagnosis — insurers often look at when signs appeared, even if a firm diagnosis came later.
• Related conditions — some policies link related problems (for example certain bilateral joint issues) so that history on one side affects the other.
• Recurring vs cured — some wordings may cover a condition again after a symptom-free period; many lifetime policies still treat once-diagnosed illnesses as ongoing for limit purposes. Never assume a “clear” year resets everything without reading the definition.
• Waiting periods — new policies usually exclude illness for a short initial period (injury cover may start sooner). Claims in that window are commonly declined.

Why vets’ notes matter so much

When you claim, insurers request clinical history. A note about intermittent limping months before cover began can be enough for a pre-existing decline on a later orthopaedic claim. That is why honesty at application and careful reading of exclusions matter — and why some owners struggle when switching insurers mid-life for a pet with a long medical record.

If a claim is declined on pre-existing grounds and you disagree with the timeline, gather full records and follow the steps in claim rejected.

Choosing cover with these terms in mind

• Decide what excess you could pay tomorrow without borrowing.
• Factor in co-insurance on a realistic large claim (thousands, not hundreds).
• Disclose your pet’s history accurately when buying cover — non-disclosure can void claims.
• For pets with known conditions, understand that new cover may exclude them permanently; specialist or specialist-referral pathways do not override policy exclusions.
• At renewal, check whether excess or co-insurance has risen with age.

Short glossary

• Fixed excess — a set pound amount you pay towards a claim.
• Co-insurance / contribution — a percentage of eligible costs you pay.
• Pre-existing condition — a problem (or its signs) present before cover or during a waiting period, usually excluded.
• Lifetime cover — typically continues to cover ongoing conditions year to year up to annual limits, while you renew — still subject to excess, co-insurance, and exclusions.

More guides: how to claim · if a claim is rejected · affiliate disclosure.