Severity-based critical illness cover pays a share of the amount insured, and the share depends on how severe the diagnosed condition is, instead of one fixed sum whenever a listed condition meets its definition. Vitality's Serious Illness Cover is built this way. Zurich, Royal London and Aviva, by contrast, pay the full sum for listed conditions and add a smaller payment for some less severe ones.
Grading by severity is hard to judge from a leaflet, so you may want an FCA-authorised broker to walk through a graded plan with you. A free call-back is what the form on this page arranges.
What does partial critical illness cover mean?
The Association of British Insurers (ABI) defines two kinds of smaller payment in its 2022 minimum-standards guide for critical illness insurers, updated in April 2023, and says the terms should be applied "Where policies provide different levels of cover":
Additional payment – this is where a claim payment made under a definition does not reduce the amount of benefit remaining. Partial payment – this is where a part payment, made in relation to a condition does reduce the amount of benefit remaining.
So the difference lies in what is left afterwards. A partial payment uses up part of the cover; an additional payment leaves the cover as it was. Insurers choose their own labels: Zurich says "Additional Payment" conditions, Royal London says "additional conditions", and Vitality talks about severity levels. Standard full-payment cover is the plainer arrangement: Aviva's summary says a successful claim on a listed condition pays the whole amount and the policy then ends.
Do not confuse these payments with additional critical illness cover, which is a way of arranging a whole policy; combined and additional critical illness cover explains it. How a standard policy works is on critical illness cover, and the ABI's wording rules are on the minimum standards page.
How does Vitality's Serious Illness Cover pay by severity?
Vitality's Personal Protection Plan Provisions (February 2025 edition) say the lump sum is a percentage of the cover "between 5% and 100%", depending on how severe the illness is, "based on a scale from A to G". Level A pays 100% and level G pays 5%. Which levels you are covered for depends on the version: 1X covers A to D, 2X covers A to E and 3X covers A to G. The full table, and the rules for later claims, are on Vitality's Serious Illness Cover.
Because each claim is a share of the cover, it also uses up that share. The Provisions say each claim "will reduce your percentage of cover remaining", and if a claim would pay more than the share left, only the share left is paid. Here is our own illustration, using invented round numbers and the percentages Vitality prints, and leaving the plan's other conditions aside:
- You hold £100,000 of Serious Illness Cover 1X. A first claim at severity C pays 50%, which is £50,000, and leaves 50% of the cover.
- A later, unrelated claim at severity A would ordinarily pay 100%. Only 50% remains, so it pays another £50,000, and a 1X plan then ends because the total paid has reached 100%.
Which level a particular diagnosis would reach is set condition by condition in the plan's conditions appendix, which the broker can go through when they phone.
On 2X or 3X, Vitality pays 100% of the cover amount for a listed set of conditions, including heart attack, multiple sclerosis and cancer (excluding less advanced cases).
How do Zurich, Royal London and Aviva pay for less severe conditions?
These three insurers do not grade every claim. Each pays the full sum for conditions on one list and a smaller amount for conditions on another, as the documents below set out.
| Insurer and document | Smaller payment | Effect on the policy |
|---|---|---|
| Zurich Life Protection, key features (February 2025) | 25% of the sum assured, up to £25,000, for an Additional Payment condition | The policy carries on as before; one claim for each such condition |
| Zurich Personal Protection, Critical Illness Enhanced Plus, key features (April 2026, adviser channel) | 50% of the sum assured, up to £50,000 | The policy carries on as before |
| Royal London Personal Menu Plan, plan details (July 2025) | 50% of the cover on a lump-sum plan, capped at £35,000 (pregnancy complications are paid at set amounts instead) | It "doesn’t affect your cover" |
| Aviva Life Insurance+, policy summary (February 2026) | 25% of the cover amount, up to £25,000, on level and decreasing cover | The policy continues; each person can claim each such illness once |
Set against the ABI's definitions, each works as an additional payment, since each document says the main cover is not reduced by it. Zurich's Personal Protection key features describe three levels, Critical Illness, Enhanced and Enhanced Plus, which differ in the lists they include and, on Enhanced Plus, in the size of the smaller payment; Zurich's critical illness cover sets out the lists. Royal London's wording is on its critical illness policy page. For the other insurers, the provider comparison sets the smaller payments side by side.
How does severity-based cover differ from standard full-payment cover?
Four things change between the two structures:
- What sets the amount. On a full-payment plan, a condition either meets its definition and pays the full sum or it does not. On Vitality's plan the amount follows the severity level.
- What remains after a claim. Zurich's key features say a full payment ends the policy. Vitality's Provisions do not cap how many claims you can make during the term, until the total paid reaches 100%, 200% or 300% of the cover amount, depending on the version.
- How a smaller payment is treated. Zurich, Royal London and Aviva keep the main cover whole after theirs. Vitality's Summary says the amount of cover remaining reduces by the amount paid.
- The same diagnosis can pay differently. Vitality's conditions appendix says cancer is included at a minimum severity of 25%, "although higher staged tumours may qualify for an increased payment", and on 2X or 3X it is lifted to 100%. Zurich Life Protection lists cancer as a full-payment condition, with less advanced breast or prostate cancer on its smaller-payment list. Conditions covered and when a claim pays go into the definitions.
These are different structures, not a ranking, and neither is better in itself. A graded plan and a full-payment plan can look alike on a quote, so ask a broker how each would pay in your situation. The short form here starts that request. Premiums are covered in what critical illness cover costs, and the wider topic in the critical illness and income guide.
Frequently asked questions
What is the smallest payment severity-based cover makes?
On Vitality's Serious Illness Cover the lowest percentage is 5%, at level G, but only the 3X version covers that level. The lowest covered level pays 25% on 1X (level D) and 15% on 2X (level E).
Does a smaller payment use up my cover?
It depends on the plan. Vitality's documents say cover remaining reduces by the amount paid, while Zurich, Royal London and Aviva say the policy carries on after their smaller payments. Your own policy documents state which applies.
Will severity-based cover always pay less than a full-payment plan?
No. Vitality's Summary says its payment "may be more than, the same as or less than" a critical illness policy would give. Which applies turns on the severity level reached and the version held.
Which conditions get a smaller payment on standard cover?
Zurich Life Protection and Aviva Life Insurance+ each name two as standard: less advanced breast cancer and less advanced prostate cancer. Zurich's Personal Protection adds an extra 31 Additional Payment conditions on its Enhanced option.
If you are weighing a graded plan against a full-payment one, an FCA-authorised broker can compare the two with you on a free call, which you set up using the form on this page.
Sources
- Association of British Insurers, ABI Guide to Minimum Standards for Critical Illness Cover (16 September 2022, updated April 2023), read 26 October 2026. abi.org.uk
- VitalityLife, Personal Protection Plan Provisions (VLTD174857WF_J3779_02/2025), adviser literature; archived copy of 21 February 2026, read 26 October 2026. web.archive.org (Vitality Provisions)
- VitalityLife, Personal Protection Plan Summary (VLTD182053WF_02/25_J8476), adviser literature; archived copy of 8 April 2025, read 26 October 2026. web.archive.org (Vitality Summary)
- Zurich, Key features of the Zurich Life Protection policy (NP720500009 02/25), read 26 October 2026. zurich.co.uk
- Zurich, Key features of the Zurich Personal Protection policy (PW720494014 04/26), adviser-channel document, read 26 October 2026. zurichintermediary.co.uk
- Royal London, Personal Menu Plan Life or Critical Illness Cover, Plan details (July 2025), hosted on its adviser site, read 26 October 2026. adviser.royallondon.com
- Aviva, Policy Summary of Life Insurance+ (AL50001 0226, February 2026), read 26 October 2026. static.aviva.io