If your life cover is a decreasing term policy and your mortgage is interest-only, the two are moving in opposite directions. The sum assured falls a little every year, on a schedule fixed when the policy started. The mortgage balance does not fall at all, because you are paying the interest and nothing else. The difference between those two lines is the amount your family would have to find from somewhere else, and it widens every year you hold both.
So, does decreasing life insurance cover an interest-only mortgage? At the start, yes. In the middle, partly. By the closing years, barely. That is not a fault in the policy — decreasing term assurance does exactly what it was built to do — it is a mismatch between a product designed to track a shrinking debt and a debt that never shrinks.
This is one of the few problems on this site you can still do something about, because you are reading it while you are alive. What follows shows you where the gap opens, how to measure your own in about ten minutes, and what the realistic options are for closing it.
At a glance
- Decreasing cover steps down each year in line with a repayment schedule. An interest-only balance has no repayment schedule, so the cover falls and the debt does not.
- At any moment, your shortfall is simply this year's sum assured subtracted from your current balance. Both figures are on paperwork you already have.
- The gap is at its widest in the final third of the term — which is also when the borrower is oldest and the risk of dying is highest.
- Level term assurance is the shape that matches an interest-only loan, because the sum assured stays put for the whole term.
- Never cancel cover you hold until replacement cover has been accepted and is on risk. Health changes, and acceptance is never guaranteed.
The short answer: the gap is the capital your policy assumes you repaid
A decreasing term policy is shaped around one assumption — that the debt behind it is being paid down. Each year the sum assured steps down by roughly the amount of capital a repayment mortgage would have cleared in that year. Where the assumption holds, the policy and the debt stay level with one another and the family is covered from the first day to the last.
On an interest-only mortgage the assumption is false from the outset. Your monthly payment settles the interest and leaves the capital untouched. The balance sits at the original amount for the whole term and then falls due in full on the final day. Every step down in the sum assured is therefore a step away from the debt rather than a step alongside it.
That gives you a clean way to think about the shortfall. At any point in the term, the gap is the capital the policy has assumed you repaid and you have not. It is not an estimate or a matter of interpretation. It is the difference between two figures you already hold: the sum assured on this year's policy schedule, and the balance on your most recent mortgage statement.
Why a decreasing policy falls at all
Decreasing term assurance exists because most mortgages in the UK are repayment mortgages, and a repayment balance genuinely does reduce. Cover that reduces with it leaves the insurer carrying less risk as the term runs on, and for the same starting sum assured it is generally the less expensive of the two shapes. That is a large part of why it gets suggested so often, and why so many people end up holding it without ever being asked what kind of mortgage they actually have.
The reduction is not linked to your real mortgage in any live sense. It follows a schedule written into the policy at outset, worked out using an assumed interest rate stated in the policy documents. That detail matters even for repayment borrowers: if your actual rate is higher than the rate the schedule assumed, your balance falls more slowly than your cover does, and a smaller version of the same problem appears. Your policy schedule, or the annual statement the insurer sends, will show the sum assured for each remaining year of the term.
Nothing in that machinery checks up on you. The insurer does not know whether you switched to interest-only three years in, took a further advance, or extended the term. The schedule set at outset simply keeps running.
Why an interest-only balance does not move
An interest-only mortgage is a loan where you have contracted to pay the interest monthly and to repay the whole capital at the end. Lenders expect a credible plan for that final repayment — a savings vehicle, an endowment, another property, a pension lump sum, or the sale of the home itself. The plan is separate from the mortgage, which is precisely why the mortgage balance never moves.
This means the last statement of the term shows the same capital figure as the first. If the plan for repaying it has failed or was never really there, the options at the end are the ones people dread: extend the term if the lender will agree, remortgage onto a retirement interest-only or later-life product, borrow against the equity, or sell. That last route is why families sometimes end up looking at how much of the house is left after a lifetime mortgage is settled rather than at an inheritance.
Death does not change any of this. The balance is unchanged, the interest keeps accruing, and somebody still has to make the monthly payment. If the household income behind that payment was self-employed earnings or dividends from a company, it may stop far more abruptly than a salary would — a trap set out in detail in our page on what happens when a director dies and the dividends stop.
The money position is identical across the UK, but the enforcement machinery is not. In England and Wales a lender that is not being paid brings possession proceedings; in Scotland it serves a calling-up notice and applies to the court under the standard security rules; in Northern Ireland the courts follow their own procedure again. None of those differences reduces the balance. They change only how long the process takes and where it happens.
The two lines, plotted side by side
Set a flat interest-only balance next to a decreasing sum assured across a standard term and the shape of the problem becomes obvious.
| Stage of the term | Interest-only balance | Decreasing sum assured | The shortfall |
|---|---|---|---|
| Year one | The full amount borrowed | The full amount borrowed | None. This is the only point at which the two match. |
| The first third | Unchanged | Edging down slowly, because a repayment schedule clears very little capital early on | Small enough to be missed entirely |
| Halfway | Unchanged | Less than half of the original sum has come off | Somewhat under half the loan |
| The final third | Unchanged | Falling steeply as the schedule accelerates | Most of the loan |
| Final year | The full amount borrowed, now due as a lump sum | Close to nothing | Close to the entire loan |
Two things in that table are arithmetic rather than opinion, and they are worth stating plainly. The first is that a repayment schedule always clears less than half of the capital in the first half of the term, at any positive interest rate at all. Early payments are mostly interest; late payments are mostly capital. So the cover line starts almost flat and then drops away.
The second is the consequence. The gap does not open at a steady rate. It is narrow and forgivable in the early years, then it widens quickly, because the sum assured is accelerating downwards at exactly the point when your balance is doing what it has always done — nothing.
The gap is widest when the risk is highest
Now put the two halves of that together. Your cover is at its lowest in the final years of the term. You are at your oldest in the final years of the term. The chance of dying within any given year rises with age, gently through the forties and more steeply after that, which is the entire basis on which life cover is underwritten and priced.
The Office for National Statistics publishes the standard UK reference for this in its national life tables, which set out the probability of dying within a year at each age. You do not have to read the tables to take the point: the years in which a decreasing policy has the least left to pay out are the same years in which it is most likely to be called upon.
Source: Office for National Statistics, National life tables, UK, published under the Open Government Licence v3.0.
That is the honest case against leaving the mismatch alone. It is not that decreasing cover is a bad product. It is that pairing it with an interest-only loan concentrates the shortfall into the period of highest risk, which is the opposite of what cover is for.
The versions of this that catch people out
The pure case — one interest-only mortgage, one decreasing policy — is the easiest to spot. Several quieter variations do the same damage.
- Part-and-part mortgages. Only the repayment portion shrinks. The interest-only portion stays where it is, so a decreasing policy taken over the whole loan drifts away from the part that never moves.
- A switch to interest-only mid-term. Borrowers who moved to interest-only during a difficult period, perhaps as a temporary concession, rarely think to tell the insurer. There is no reason they would. But the cover carries on falling as though capital were still being repaid.
- Further borrowing. A further advance or a remortgage at a higher amount pushes the balance up while the old policy continues its descent — two moves in opposite directions on the same day.
- A term extension. Pushing the mortgage out to a later end date leaves the policy expiring first, which produces a stretch at the end with no cover at all rather than merely too little.
- Cover held by only one of you. Where a joint application produced one acceptance and one refusal, the survivor's position depends entirely on which of you died — the situation we cover in what happens when only one of you is accepted for cover.
One more thing worth checking while the paperwork is out: whether the policy is assigned to the lender. An assignment sends the payout to the mortgage account directly rather than to your family, which is fine where the amounts line up and awkward where they do not. Our page on life cover assigned to the mortgage lender explains how to tell and what it changes.
How to measure your own gap in ten minutes
You need two documents: your latest mortgage statement and your policy schedule or annual insurance statement. Then work through this in order.
- Write down the current balance, and note whether the statement describes the loan as interest-only, repayment or part-and-part. If it is part-and-part, note the interest-only portion separately.
- Write down this year's sum assured from the policy schedule, and the date the policy ends.
- Subtract the second from the first. That is today's shortfall, and it is the smallest it will ever be.
- Find the sum assured for the final year of the policy on the same schedule and subtract that from the same balance. That is the shortfall your family would face at the worst point in the term.
- Compare the two end dates. If the mortgage runs on past the policy, there is a period at the end with no cover at all — a separate problem from the one you came here for, and a more serious one.
- Check whether the policy is written in trust, assigned to the lender, or neither. That determines who receives the money and how quickly it arrives, and it is far easier to sort out now than during probate.
If those figures come out uncomfortably, that is the correct reaction and it is also useful information. You now know the size of the problem rather than suspecting it.
Closing the gap without losing the cover you already have
There are three sensible routes, and one rule that overrides all of them.
The rule first: do not cancel an existing policy until the replacement has been accepted, the premium has been collected and the insurer confirms the cover is on risk. Your health today is not the health you were underwritten on, and a policy in force is worth more than an application in progress. If you have already been refused cover once, the position is not hopeless but it does need care — we set out the practical options in our page on being declined for cover after a mortgage offer.
The routes themselves. The first is to replace the decreasing policy with level term assurance for the amount of the interest-only balance, running at least as long as the mortgage does. That matches a flat debt with flat cover and removes the mismatch entirely. The second is to leave the existing policy alone and add a separate level policy alongside it for the interest-only portion, which suits part-and-part borrowers and anyone whose original policy was underwritten when they were younger and in better health. The third, where the term is what is wrong rather than the amount, is to extend or replace the cover so that it outlives the mortgage.
Whichever route fits, the amount and the term should be set against your real balance and your real end date, not against a figure someone worked out years ago. An FCA-authorised broker can make that comparison across insurers, and you can get life insurance quotes to see what level cover for your balance and term would involve. What any insurer will offer depends on underwriting — age, medical history, occupation — so acceptance and terms are settled on the application rather than in advance.
One last detail that catches executors out. Where cover does pay and the mortgage is redeemed years ahead of schedule, families sometimes fear being penalised for repaying early. Usually they are not, but it turns on the lender and the loan, which is why it is worth knowing in advance whether an early repayment charge applies when the borrower dies. The rest of this subject, including what happens to the property and the estate, is collected in our guide to mortgages and property when someone dies.
Frequently asked questions
Does decreasing life cover suit an interest-only mortgage?
It is a poor match. Decreasing term assurance is designed to track a repayment mortgage as capital is paid off, whereas an interest-only balance stays at the original amount from the first day of the term to the last. The cover falls each year while the debt does not, so a gap opens and then widens — and it is at its largest in the final years, which are also the years when a claim is most likely.
What type of cover fits an interest-only loan?
Level term assurance keeps the sum assured constant for the whole term, which mirrors a balance that never reduces. The term should run at least as long as the mortgage does, because the capital falls due in full at the end of it, and cover that expires first leaves the worst period uncovered.
Can I switch from decreasing to level cover?
You would normally apply for a new level term policy rather than convert the existing one, and what an insurer offers reflects your age and health at the time of applying. Keep the old policy in force until the new one has been accepted and is on risk. Cancelling first leaves a gap, and if your health has changed since the original application the replacement may come with different terms, or may not be offered at all.