Mortgages, plainly explained
A mortgage is the biggest loan most people ever take on, yet it’s wrapped in more jargon than almost anything in personal finance. Strip that away and it’s simple: a loan to buy a property, secured against that property — so if you don’t keep up repayments, the lender can ultimately repossess it. Understanding the handful of moving parts turns a bewildering process into a series of clear decisions.
This is information, not financial advice. Mortgages are regulated products and your home may be repossessed if you don’t keep up repayments. A mortgage broker or adviser can recommend what’s right for you.
The parts of a mortgage
Every mortgage comes down to a few numbers:
- The deposit — the cash you put in up front, usually a percentage of the price.
- The loan — the rest, borrowed from the lender.
- Loan-to-value (LTV) — the loan as a percentage of the property’s value. Borrow £180,000 on a £200,000 home and that’s a 90% LTV. This number matters enormously, because the lower your LTV, the lower the interest rates you can access. Rates step down at 90%, 85%, 80%, 75% and 60% LTV — so nudging your deposit past one of those thresholds can cut your rate.
- The term — how many years you spread the loan over (often 25–35). A longer term means lower monthly payments but more interest overall.
- The interest rate — what the borrowing costs.
See how those numbers combine. Change the price, deposit, rate and term and watch the monthly payment, your LTV and the total interest move:
Repayment vs interest-only
There are two ways to pay a mortgage back:
- Repayment (capital and interest). Each monthly payment covers the interest and chips away at the loan, so by the end of the term you owe nothing. This is how almost all residential mortgages work — you’re steadily buying your home.
- Interest-only. You pay just the interest each month, so payments are lower — but you still owe the whole loan at the end and need a separate plan to repay it. Common for buy-to-let, rare and tightly controlled for ordinary home-buyers.
For most people buying a home to live in, repayment is the norm.
Fixed, tracker or variable?
The interest rate comes in a few flavours, and this is the main choice you’ll make:
- Fixed rate. Your rate is locked for a set period (commonly 2, 3, 5 or 10 years). Your payments can’t change during that time — certainty, which many people value, even if it’s not always the cheapest.
- Tracker. Your rate follows the Bank of England base rate plus a set margin, so it moves up and down. Cheaper when rates fall; pricier when they rise.
- Standard variable rate (SVR). The lender’s default rate, which you roll onto when a deal ends. It’s usually expensive — which is exactly why you don’t want to sit on it.
When a deal ends, remortgaging (moving to a new deal, with your current lender or another) is how you avoid the SVR. Start looking around six months before your deal finishes.
The costs beyond the rate
The headline rate isn’t the whole story:
- Arrangement/product fees can run to a four-figure sum. A low rate with a big fee can cost more overall than a higher rate with none — compare the total cost over the deal period.
- Valuation and legal fees, and possibly a broker fee.
- Early repayment charges (ERCs) — a penalty for leaving a fixed deal early, often a percentage of the balance. Important if you might move or overpay a lot.
How much can you borrow?
Lenders assess affordability — your income, outgoings, existing debts and credit history — and “stress test” whether you could still pay if rates rose. As a rough guide, borrowing tends to top out around 4 to 4.5 times income, but it varies. Getting an agreement in principle early tells you your likely budget before you house-hunt.
Where to start
The two highest-value moves are simple: build the biggest deposit you can (to drop your LTV into a cheaper band), and never drift onto the SVR (remortgage before each deal ends). Because mortgages are regulated and the stakes are high, a whole-of-market mortgage broker is genuinely worth it — they can search deals you can’t and handle the paperwork, often for a modest fee or none.
Last checked 1 August 2026. General information on how UK mortgages work; not a recommendation of any product.
Sources
Just so you know: this guide is information and journalism, not financial advice, and we don't recommend specific financial products. Your circumstances are your own — if you need personal advice, speak to a suitably qualified adviser. Information was correct at the "last updated" date above but things change; always check the linked primary sources.