How Does a Mortgage Work? (2026): The Complete Beginner’s Guide
A mortgage is simply a loan to buy a home, secured against the property. But understanding how the deposit, interest, term and repayments fit together is what helps you borrow well. Here’s the whole thing explained clearly, from what a mortgage is to how you pay it off.
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Quick answer
A mortgage is a loan you take out to buy a property, secured against that property — meaning if you don’t keep up repayments, the lender can ultimately repossess the home. You pay a deposit (typically 5–10% or more of the price) and borrow the rest from a bank or building society, then repay it monthly, with interest, over an agreed term that’s usually around 25 years. Everything about how a mortgage works comes down to four things: how much you borrow, how you repay it, the interest rate you pay, and whether the lender is satisfied with your income, deposit, credit history and the property. The size of your deposit sets your loan-to-value (LTV) — the percentage of the property’s value you’re borrowing — and a lower LTV (bigger deposit) unlocks better interest rates. Most people take a repayment mortgage, where each monthly payment clears a slice of the loan plus the interest, so the debt is fully gone by the end of the term. Interest is the cost of borrowing, and because it’s charged on what you still owe, early payments are mostly interest and later ones mostly capital. Once you understand these building blocks — deposit, LTV, interest, term and repayment type — the rest of the mortgage world makes sense. This is general information, not advice. As of September 2026.
In this guide
What a mortgage actually is
At its simplest, a mortgage is a loan used to buy a property, secured against that property. Because most people don’t have hundreds of thousands of pounds in cash, they put down a deposit and borrow the rest from a lender — a bank or building society — paying it back over many years. The word “secured” is important: it means the property acts as the lender’s guarantee. If you keep up your repayments, the home is yours and the debt gradually disappears. If you stop paying, the lender has the right to repossess and sell the property to recover what it’s owed. That security is why mortgage interest rates are much lower than, say, credit card rates — the lender is taking less risk. Everything else about mortgages flows from four simple questions: how much you borrow, how you repay it, what interest rate you pay, and whether the lender is comfortable lending to you (based on your income, deposit, credit profile and the property itself). Get your head around those four, and the whole subject becomes far less intimidating. The rest of this guide walks through each building block in plain English.
Deposit & loan-to-value (LTV)
Your deposit sets your LTV — and your LTV drives your rate
Your deposit is the cash you put in yourself. The minimum is usually 5% of the purchase price, though many buyers aim for 10% or more because it opens up more deals and better rates. The deposit determines your loan-to-value (LTV) — the size of your mortgage as a percentage of the property’s value. On a £250,000 home:
| Deposit | Mortgage | LTV |
|---|---|---|
| 5% (£12,500) | £237,500 | 95% |
| 10% (£25,000) | £225,000 | 90% |
| 15% (£37,500) | £212,500 | 85% |
| 25% (£62,500) | £187,500 | 75% |
| 40% (£100,000) | £150,000 | 60% |
LTV matters enormously because lenders price mortgages in LTV bands, and lower LTVs get better rates — the big improvements typically come at the 90%, 85%, 75% and 60% thresholds. A bigger deposit means the lender is risking less, so it rewards you with a cheaper rate. That’s why saving a little more for your deposit — enough to drop into the next band down — can save you thousands over the mortgage. Our guide to loan-to-value goes deeper, and if you’re still building your deposit, see the average house deposit and the Lifetime ISA (which adds a 25% government bonus).
How mortgage interest works
Interest is the cost of borrowing — the lender’s charge for lending you the money, expressed as a percentage rate. Here’s the key thing many people don’t realise: interest is charged on the amount you still owe, not on the original loan. So as you gradually pay down the balance, the interest portion of each payment shrinks. This has a striking effect on a repayment mortgage. Take a £200,000 mortgage at 4.5% over 25 years, where the monthly payment is about £1,112:
- Your very first payment is roughly £750 interest and only £362 capital — because you owe the full £200,000, so the interest is high.
- By year 21, the same £1,112 payment is about £224 interest and £888 capital — because you now owe much less, so far more goes toward clearing the debt.
This gradual shift is why mortgages feel slow to reduce at first and then accelerate. It also explains why the total interest you pay is so large: on that £200,000 loan at 4.5% over 25 years, you’d repay around £333,000 in total — about £133,000 of it interest. At 4% it’s roughly £117,000 interest; at 5%, around £151,000. Even small rate differences matter over 25 years, which is exactly why your deposit (and the LTV band it puts you in) is worth optimising. You can see the numbers for your own situation with our mortgage repayments tables, and reduce the interest you pay through overpayments.
How you repay: capital vs interest-only
There are two fundamental ways to repay a mortgage, and the difference is huge:
- Repayment (capital and interest) — the standard, and what most people have. Each monthly payment covers the interest plus a slice of the actual loan (the capital), so the balance steadily falls and the mortgage is fully paid off by the end of the term. You own your home outright at the finish.
- Interest-only — each monthly payment covers only the interest, so the payments are lower, but the original loan amount doesn’t reduce at all. At the end of the term you still owe the full amount and must repay it in one go, usually from savings, investments or selling the property. Interest-only is common for buy-to-let but restricted for residential mortgages, because you need a credible plan to repay the capital.
For the vast majority of homebuyers, a repayment mortgage is the right and safest choice, because it guarantees you’ll own your home debt-free at the end. Our guide comparing repayment vs interest-only explains the full trade-offs and when interest-only can make sense.
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The mortgage term
The term is how long you take to repay the mortgage. The traditional term is 25 years, but lenders offer anything from around 5 to 40 years, and longer terms have become more common as prices have risen. The term involves a clear trade-off: a longer term means lower monthly payments but more interest overall, while a shorter term means higher monthly payments but less total interest. On a £200,000 mortgage at 4.5%, for example:
| Term | Monthly payment | Total interest |
|---|---|---|
| 20 years | ~£1,265 | ~£104,000 |
| 25 years | ~£1,112 | ~£133,000 |
| 30 years | ~£1,013 | ~£165,000 |
| 35 years | ~£947 | ~£198,000 |
So stretching from 25 to 35 years cuts the monthly payment by around £165 but adds roughly £65,000 in total interest. Many buyers choose a longer term for affordability and then shorten it later (through overpayments or at remortgage) as their income grows. Our guide to the mortgage term covers choosing, extending and shortening it.
Fixed vs variable rates
Your interest rate can either be locked or move over time, and choosing between them is one of the main decisions when you take a deal:
- Fixed rate — your rate (and monthly payment) is locked for a set period, commonly 2 or 5 years, giving you certainty regardless of what happens to interest rates. When the fixed period ends, you move onto the lender’s standard variable rate unless you remortgage. See fixed-rate mortgages.
- Variable rate — your rate can change. This includes trackers (which follow the Bank of England base rate plus a set margin) and the lender’s standard variable rate. Payments can go up or down.
Most people choose a fixed rate for the peace of mind of knowing exactly what they’ll pay. When any initial deal period ends, you typically remortgage onto a new deal to avoid slipping onto the more expensive standard variable rate — this cycle of taking a deal, then switching every few years, is a normal part of having a mortgage. There are also many specialised mortgage types beyond the basics — for the full range, see our mortgage types hub.
The mortgage journey, step by step
Putting it all together, here’s how getting a mortgage actually unfolds from start to finish:
- 1. Work out your budget. Understand how much you can borrow (lenders typically lend around 4–4.5× your income) and what deposit you have. Our how much can I borrow guide is the place to start.
- 2. Get a Mortgage in Principle. A lender’s initial indication of what it would lend, useful for house-hunting — see mortgage in principle.
- 3. Find a property and make an offer. Once accepted, you apply for the actual mortgage.
- 4. Apply and get assessed. The lender checks your income, credit, deposit and the property (including a valuation), then issues a formal mortgage offer. See how to apply.
- 5. Conveyancing and completion. Solicitors handle the legal work; on completion the money is transferred, the property is yours, and your monthly payments begin. The whole process typically takes a couple of months — see how long a mortgage takes.
A mortgage broker guides you through all of this, comparing the whole market to find the right lender and handling the application — which is why most buyers use one. If you’re a first-time buyer, our dedicated guide walks through the journey in more detail.
The bottom line
A mortgage is a loan to buy a home, secured against the property, repaid monthly with interest over a term that’s usually around 25 years. It all comes down to four things: how much you borrow, how you repay it, the interest rate, and whether the lender is comfortable lending to you. Your deposit sets your loan-to-value, and a lower LTV unlocks better rates. Most people take a repayment mortgage, clearing capital and interest so they own the home outright at the end, and interest is charged on what you still owe — so early payments are mostly interest, later ones mostly capital. Choose a term that balances affordable monthly payments against total interest, and a fixed or variable rate to suit your appetite for certainty. Understand these building blocks and you’re well equipped — and a broker handles the rest.
Ready to take the next step? Get matched with an FCA-regulated, whole-of-market broker who’ll guide you through it all — free, no obligation.
How mortgages work: FAQs
How does a mortgage work in simple terms?
A mortgage is a loan you use to buy a property, secured against that property. You pay a deposit (usually at least 5–10% of the price) and borrow the rest from a bank or building society, then repay it in monthly instalments, with interest, over an agreed term that’s typically around 25 years. Because the loan is secured on your home, the lender can repossess the property if you don’t keep up repayments — which is also why mortgage interest rates are lower than most other borrowing. With the most common type, a repayment mortgage, each monthly payment clears some of the interest and some of the actual loan, so by the end of the term the debt is fully paid off and you own your home outright. The key factors are how much you borrow, your deposit, the interest rate, and the term.
How does interest work on a mortgage?
Interest is the cost of borrowing, charged as a percentage rate on the amount you still owe — not on the original loan amount. This is important: because interest is calculated on your outstanding balance, it reduces as you pay the loan down. On a repayment mortgage, this means your early payments are mostly interest and very little capital, while your later payments are mostly capital and little interest. For example, on a £200,000 mortgage at 4.5% over 25 years (about £1,112 a month), your first payment is roughly £750 interest and £362 capital, but by year 21 it’s around £224 interest and £888 capital. Over the full term you’d pay around £133,000 in interest on top of the £200,000 borrowed. This is why even a small difference in your interest rate, or a slightly larger deposit that gets you a better rate, can save you thousands.
How much deposit do I need for a mortgage?
The minimum deposit for most mortgages is 5% of the property’s purchase price, though not all lenders offer 95% mortgages and those that do often charge higher interest rates. Many buyers aim for 10% or more, because a bigger deposit opens up significantly more mortgage products and better rates. Your deposit determines your loan-to-value (LTV) — a 10% deposit means a 90% LTV mortgage, a 25% deposit means 75% LTV. Lenders offer their best rates at lower LTVs, with notable improvements typically at the 90%, 85%, 75% and 60% thresholds, because a larger deposit means less risk for them. So while 5% is possible, saving a little more to reach the next LTV band down can save you a significant amount over the life of the mortgage. On a £250,000 home, a 10% deposit is £25,000 and a 15% deposit is £37,500.
What’s the difference between repayment and interest-only?
With a repayment mortgage — the standard type for homebuyers — each monthly payment covers the interest plus a portion of the actual loan (the capital), so the balance steadily reduces and the mortgage is fully paid off by the end of the term, leaving you owning your home outright. With an interest-only mortgage, your monthly payments cover only the interest, so they’re lower, but the original loan amount doesn’t reduce at all — at the end of the term you still owe the full amount and must repay it in one lump sum, usually from savings, investments or selling the property. Interest-only is common for buy-to-let but restricted for residential mortgages, as lenders need to see a credible plan to repay the capital. For most homebuyers, a repayment mortgage is the safest choice because it guarantees the debt is cleared by the end.
How long is a typical mortgage?
The traditional and most common mortgage term is 25 years, but lenders offer terms ranging from around 5 to 40 years, and longer terms have become increasingly common as house prices have risen. The term you choose involves a trade-off: a longer term reduces your monthly payments but increases the total interest you pay over the life of the mortgage, while a shorter term means higher monthly payments but less total interest. For example, on a £200,000 mortgage at 4.5%, a 25-year term costs about £1,112 a month with roughly £133,000 total interest, while stretching to 35 years cuts the monthly payment to about £947 but adds around £65,000 more in total interest. Many buyers choose a longer term initially for affordability, then shorten it over time through overpayments or when they remortgage as their income grows.
Do I need a mortgage broker to get a mortgage?
You don’t legally need a broker — you can apply directly to a lender — but most UK buyers use one, and for good reason. A whole-of-market mortgage broker compares deals across the entire market, matches you to a lender whose criteria suit your circumstances, and handles the application on your behalf, which is especially valuable if your situation is anything other than straightforward (self-employed, adverse credit, first-time buyer, or an unusual property). Going direct to a single lender means you only see that lender’s deals and get no independent comparison. A broker can also access some products not available directly to the public. Many brokers are fee-free, earning their money from lender commission. Getting matched to an FCA-regulated, whole-of-market broker is a simple way to ensure you’re seeing the right options for your circumstances rather than guessing.
Important information
nextmove is an introducer, not a lender or mortgage adviser. This article is general educational information only and does not constitute financial advice. Interest rates, deposit requirements, loan-to-value bands, terms and lending criteria vary between lenders and change over time; the figures and worked examples here are illustrative, based on 2026 assumptions, and not quotes — your actual mortgage depends on your circumstances, the lender and the market. We introduce you to FCA-regulated, whole-of-market mortgage brokers who can explain your options and advise, and we may receive a fee or commission for doing so.
Your home may be repossessed if you do not keep up repayments on your mortgage.
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