No — and hold onto that plainly, because the history of this subject is a history of people being told otherwise. No UK lender requires critical illness cover as a mortgage condition: not for approval, not for completion, not buried in the small print. Life insurance is often expected (some lenders make it a condition, and it’s sensible anyway when a family shares the debt — the full picture lives in our guide to whether life insurance helps you get a mortgage), but critical illness cover is always a choice, and any adviser presenting it as mandatory is selling, not advising. The honest reframe once the myth is cleared: the question isn’t whether the lender needs you to have it — it’s whether your household could carry the mortgage through eighteen months of chemotherapy on statutory sick pay. For many families the answer makes CI cover genuinely attractive on its own merits; for others, savings, employer sick pay or income protection answer it better. Buy it because the maths says so for your house — never because someone implied the bank demands it.

Match it to the mortgage’s shape. A repayment mortgage shrinks every month, so decreasing cover — where the sum insured falls roughly in step with your outstanding balance — protects exactly what’s owed at meaningfully lower premiums; it’s the natural fit for most homeowners and the structure most combined mortgage policies use. An interest-only mortgage doesn’t shrink at all, so it needs level cover holding the full amount to the end. The nuances worth knowing before signing: decreasing policies assume an interest rate for their glide path (commonly around 7-8%) — if your mortgage rate ever exceeds the policy’s assumed rate, a gap can open between cover and balance, worth a question at purchase; overpaying your mortgage faster than the policy decreases is harmless (cover simply exceeds debt); and remortgaging to borrow more is the moment to review, since your old policy knows nothing about the new balance. One honest alternative to the pure-decreasing default: some households deliberately buy level cover on a repayment mortgage, accepting higher premiums so that early-years claims — when the balance is biggest and children youngest — come with surplus beyond the debt. Neither answer is wrong; the mortgage’s shape plus your appetite for surplus decides.

Meaningfully more than the life-only policy — that’s the honest headline, because critical illness is claimed far more often than death during a mortgage term, and premiums price that probability. The variables that set your number: age at application (the permanent lever — every year waited is locked into every future premium), smoking (roughly doubles it), health history (conditions mean loadings or exclusions, and CI underwriting runs stricter than life), the sum and term, decreasing versus level, and guaranteed versus reviewable premiums — take guaranteed where offered, because reviewable’s five-yearly reassessments are the mechanism behind most renewal-shock stories. The pragmatic cost lever most buyers never consider: partial cover. Full mortgage-sized CI protection is expensive; cover sized to buy your family two or three mortgage-free years — space to recover, adapt, or sell well rather than desperately — costs a fraction and delivers most of the real-world protection. A sustainable partial sum beats a heroic full one that gets cancelled in year three, and whole-market comparison matters more in CI than almost any product, because insurer appetite for your particular health profile varies enormously.

On most combined policies — it ends, and this is the single most important structural fact to understand before buying. The standard combined product is ‘accelerated’ cover: one sum insured paying on death or critical illness, whichever strikes first. Claim for cancer at 43 and the policy does its job — the mortgage clears — but the life insurance dies with the claim, leaving you a cancer survivor seeking new life cover at survivor prices, if it’s offered at all. The alternatives, in rising order of cost: ‘additional’ or independent structures within one policy, where the critical illness sum and life sum are separate — a CI claim pays out and the life cover stands; buying separate standalone policies, achieving the same independence with more admin; or Vitality’s Serious Illness Cover architecture, where 2X and 3X plans continue paying claims even after a full payout. None of this makes accelerated cover wrong — it’s the cheapest way to cover both risks, and for tight budgets that matters — but it makes the question compulsory: if illness strikes, does your family need the house paid AND the life cover intact? If yes, price the separated structures before defaulting to the combined quote everyone’s handed first.