Critical illness cover pays a tax-free lump sum if you're diagnosed with a specified serious condition and survive for a set period: usually around 10 to 14 days, though it varies by insurer. It's designed to ease the financial impact of a major illness, giving you a cash sum to use however you need: clearing a mortgage, covering time off, adapting your home or simply taking the pressure off while you recover.

What's typically covered

Most policies cover around 40 to 50 conditions, including cancer (subject to type and staging), heart attack, stroke with permanent symptoms, multiple sclerosis, major organ transplant, and total and permanent disability. Some insurers now cover over 100 conditions, often split into full-payment and partial-payment tiers, where less severe conditions pay a smaller percentage of the sum assured. Cancer is by far the most common reason for a claim, accounting for around 62% of critical illness payouts according to ABI figures.

How often does it actually pay out?

Despite a reputation for declined claims, the large majority are paid. Industry figures show that roughly 90% of critical illness claims are paid, and the average payout in 2024 was around £67,600. Where claims aren't paid, it's usually for one of two reasons: the condition didn't meet the policy's precise definition, or the applicant didn't fully disclose their medical history when taking out the policy. Both are largely avoidable: which is why honest, complete disclosure and a clear understanding of the definitions are so important.

What it doesn't cover

Critical illness is not life insurance: if you die before the survival period without a qualifying diagnosis, no critical illness benefit is payable (though many policies combine the two). It's also not income protection: the lump sum is paid once, and the policy then ends, rather than providing an ongoing monthly income. And it only pays for the specific conditions listed, at the severity defined: a milder version of a listed condition may not meet the threshold.

Getting the definitions right

The ABI publishes model wordings that set a baseline for common conditions, but insurers vary significantly: particularly for cancer, where some exclude certain early-stage or non-invasive tumours, and for conditions like heart attack and stroke, where the precise medical criteria differ. Two policies at a similar price can offer noticeably different real-world protection. This is exactly where comparing definitions, not just premiums, makes the difference.

Standalone or combined with life cover?

Critical illness is often bought alongside life insurance, either as a combined policy that pays out on the first event (diagnosis or death), or as additional cover that pays separately. Combining can be cost-effective, but a combined policy usually ends after the first claim: so if it pays out on a critical illness, the life cover may stop. Whether to combine or keep them separate depends on what you're trying to protect.

Guaranteed or reviewable premiums?

Premiums come in two main forms. Guaranteed premiums stay the same for the life of the policy, so you know exactly what you'll pay. Reviewable premiums can start lower but may be increased by the insurer at set review points, sometimes substantially. Guaranteed cover often works out more predictable over a long term, but the right choice depends on your budget and how long you need the cover.

Children's cover and added features

Many policies include some cover for the policyholder's children as standard, paying a smaller lump sum if a child is diagnosed with a listed condition. Other features to look for include the range of partial-payment conditions, the total and permanent disability definition, and whether any cover continues after a claim. These extras can matter as much as the headline condition count.

How much cover do you need?

A useful starting point is to think about what the money would need to do: clear or reduce a mortgage, cover a period out of work, fund adaptations to your home, or pay for treatment and care. Because it pays a single lump sum, critical illness cover is often used to remove a specific financial shock rather than replace income over time: which is where income protection comes in. It's worth reviewing your cover after big life changes, such as a new mortgage or a child.

The bottom line

Critical illness cover can provide vital financial breathing space at a frightening time, and most valid claims are paid. The key is to compare policies on their condition definitions and disclose your history fully, rather than choosing on price alone. An independent adviser can help you compare like for like and match the cover to your circumstances.