Should I clear the mortgage?

Start here, because for a large minority of people it ends the conversation in ten minutes.

A mortgage at 3% while inflation runs at 4% is not costing you 3% — it is costing you minus 1% in real terms. The debt is a fixed number that gets easier to carry every year while everything else, including your income and the value of the house, drifts upward around it. That is a genuinely unusual thing to own, and clearing it early throws it away.

Now the direct comparison: the same lump sum against the mortgage, or into the market. This is the version of the question most people think they're asking.

The most useful output is not either net worth figure. It is the break-even return — the return your investments would have to beat for keeping the mortgage to have been the right call. That converts a vague argument into a single question you can actually answer: would I bet on beating that, after tax and fees, over this horizon?

Steps 1 and 2 framed this as mortgage versus market. It isn't. The same lump sum could sit in cash as a buffer, go to your children while you're alive to watch, or be spent on the decade when you're still well enough to enjoy it.

This calculator lays all five side by side over the same horizon. A surprising number of people find that the option they were agonising over was not the best use of the money at all — and that the two they had never seriously considered are the ones worth thinking about.

If you do only one of these eight, do this one.

The most common serious mistake in this whole decision is not choosing wrong between mortgage and market. It is clearing the mortgage with money you turn out to need. Being debt-free with £3,000 accessible is a worse position than owing £80,000 with two years of spending in the bank — because the first situation has no answers when the boiler goes, and the second has plenty.

Money in the house is not money you can reach. Releasing it again means selling, remortgaging on retirement income, or equity release, and all three are slow, expensive or both — and all three get harder in exactly the circumstances that would make you need them.

Step 2 compared averages. This one compares survival, and it frequently reverses the conclusion.

Here is why. If you keep the mortgage and invest the lump sum, a crash in your first years of retirement hits a larger portfolio that must also fund a mortgage payment — so you are selling more units at the bottom, every month, to make that payment. If you cleared the loan instead, you have a smaller portfolio but a permanently smaller withdrawal, and the smaller withdrawal is what carries you through. A smaller pot with no repayment can be considerably more robust than a bigger one with one.

If steps 2 and 5 disagree — investing wins on average but loses on failures — you have found the real shape of your decision. Which one you weight more is a question about you, not about arithmetic: are you optimising for the best likely outcome, or for the worst tolerable one? In retirement, most people should be doing the second, and most people's instincts do the first.

Only relevant if you've landed on keeping the mortgage — but essential if you have.

The ratios your lender used — debt to income, loan to value — were designed for someone with a salary that rises. In retirement your income is flat or falling, some of it stops, and only part of it is guaranteed for life. A debt that was comfortable on a salary can be quietly unsustainable on a pension without any number on your statement changing.

This decision is not binary, and treating it as binary is how people end up at one of the two extremes when the sensible answer was in between.

You can pay down part of the loan — enough to bring the repayment to a figure your guaranteed income covers on its own — and keep the rest of the lump sum accessible. That gets you most of the security of clearing it, keeps most of your liquidity, and leaves the inflation subsidy from step 1 working on the remaining balance.

This calculator works backwards from the repayment you want to the lump sum required. Try setting the target repayment to whatever your guaranteed income comfortably covers, and see what it costs. For a lot of people that number is far smaller than the full balance, and it buys most of the peace of mind.

A different question, and only relevant if you got to step 4 and found the honest answer was "I have no lump sum to deploy at all — everything I own is the house."

That is a common and uncomfortable position, and equity release exists for it. It is not automatically a bad product; for someone asset-rich and cash-poor it is sometimes the right answer. But the price is real and it is paid by whoever inherits, because unpaid interest compounds — at 7%, a debt roughly doubles every decade while you do nothing at all.