These two products get compared as though they were competing answers to one question. They are not. They are answers to two different questions, and the reason people end up with the wrong one is that nobody ever puts the questions side by side.
Income protection asks: what if you cannot earn?
Critical illness cover asks: what if you are diagnosed with something specific?
You can be seriously ill and find one of them pays in full while the other pays nothing at all.
What each one actually does
Income protection insurance covers some of the income you lose if you cannot work because you are ill or injured. It pays a regular income until you retire or are able to return to work, and it covers most illnesses that leave you unable to work — subject to the policy's own definition of incapacity. Crucially, it can be claimed as many times as you need while the policy lasts.
Critical illness cover pays out if you are diagnosed with one of the specific medical conditions or injuries listed in the policy. The most common are stroke, heart attack and certain types of cancer. It pays out once, after which the policy ends.
So one is a replacement income with a tap that can be turned on and off. The other is a single payment triggered by a name on a list.
The four cases that show the difference
This is where the abstraction becomes concrete. Consider four situations.
A back injury stops you working for two years. Income protection pays throughout. Critical illness pays nothing — a back injury is not on the list.
You are diagnosed with an early-stage cancer, treated successfully, and keep working throughout. Critical illness pays the lump sum, assuming the diagnosis meets the policy's severity definition. Income protection pays nothing, because you never stopped earning.
A severe stroke leaves you unable to work permanently. Both pay. Critical illness pays its lump sum and ends. Income protection continues paying monthly, potentially for decades.
A long depressive illness keeps you off work for eight months. Income protection is likely to pay, subject to the policy's incapacity definition. Critical illness almost certainly pays nothing.
Look at the pattern. Critical illness is narrow and binary — a named condition, at a defined severity, paid once. Income protection is broad and continuing — most illnesses, for as long as they stop you earning.
Why the list matters more than people expect
The word "critical" invites an assumption: that anything genuinely serious will be covered. It will not. What is covered is what the policy's list says is covered, at the severity the policy defines.
Two people with what sounds like the same diagnosis can get different answers, because the policy specifies not just the condition but how advanced or severe it must be. This is the single largest source of disappointment with these policies, and it is not a scandal — it is what the contract says, in writing, before anyone signs.
If you are considering critical illness cover, the list and its definitions are the product. Read them, or have an adviser read them to you. Comparing two policies on premium alone compares the wrong thing.
The deferred period is the decision people rush
Income protection has a deferred period — the wait between being unable to work and the policy beginning to pay. A longer deferred period lowers the premium, which is exactly why it gets chosen carelessly.
It should be set against the ground covered in what the state actually pays if you cannot work:
- If your employer pays full salary for six months, a policy paying from month one is buying cover you already have.
- If your employer pays nothing above Statutory Sick Pay, the gap opens almost immediately — and SSP stops entirely at 28 weeks.
- If you are self-employed, there is no SSP and no employer scheme at all, so the deferred period is the whole decision.
The right deferred period is the one where your existing income stops. Working that out takes ten minutes with an employment contract and is worth more than any amount of comparing quotes.
How to decide between them
Start from the shortfall rather than the product.
Income protection suits you if a long absence from work would break the monthly budget — a mortgage or rent that has to be paid every month regardless, and no other household income that could carry it. This is most people who work for a living.
Critical illness suits you if a specific serious diagnosis would create a one-off need: clearing a mortgage, adapting a home, paying for a period where a partner stops working to provide care, or simply removing money from a decision you would rather make on medical grounds.
They are frequently held together rather than as alternatives — critical illness cover is typically taken out alongside life insurance or income protection. But "get both" is a sales answer, not a plan. The plan starts with the number you cannot absorb.
If the question is what happens to your family after a death rather than during an illness, that is a third and separate calculation — set out in how much life insurance you need, and, for anyone whose estate may face inheritance tax, in why a policy is written in trust.
What to actually check
- What stops first — your employer's sick pay, or your savings? That date sets the deferred period.
- What is your actual monthly shortfall, not your salary? Income protection replaces part of income, not all of it.
- On any critical illness policy: the condition list and the severity definitions. That is the product.
- Would a lump sum or a monthly income solve your problem? They are not interchangeable.
- Are you self-employed? There is no SSP behind you, which changes both answers.
This article explains how the two products differ. It is not financial advice and it is not a recommendation of either. Policy terms, incapacity definitions and condition lists vary significantly between insurers, and what suits you depends on your income, your outgoings and your health. Take advice from an FCA-regulated protection adviser before buying.
Sources
- MoneyHelper — What is income protection insurance? (opens in a new tab)
- MoneyHelper — What is critical illness cover? (opens in a new tab)
- MoneyHelper — How to know what kind of protection insurance you need (opens in a new tab)
- GOV.UK — Statutory Sick Pay: what you'll get (opens in a new tab)
- FCA — Structure of the UK pure protection market for retail customers (opens in a new tab)
This article is general information for a United Kingdom audience. It is not financial advice and it is not a recommendation of any product or insurer. Policy terms, definitions of incapacity and lists of covered conditions vary considerably between providers, and only the policy document governs a claim. Take advice from an FCA-regulated adviser before buying protection insurance. Last reviewed 15 September 2026.
