UK mortgages explained: LTV, terms and what drives your payment
Money · 7 min read
A mortgage is the biggest financial commitment most people in the UK ever take on, yet the jargon around it is dense and off-putting. This guide breaks down the moving parts, loan-to-value, interest rate, term and repayment type, so you can understand what actually sets your monthly payment and how small changes ripple through the maths. As always, treat any numbers here as estimates rather than financial advice; a mortgage adviser can look at your specific circumstances.
What loan-to-value actually means
Loan-to-value, or LTV, is simply the size of your mortgage as a percentage of the property's value. If you buy a £250,000 home with a £25,000 deposit, you are borrowing £225,000, which is 90% LTV. Lenders use this figure to price risk: the less of your own money you have in the property, the more exposed the lender is if prices fall or you cannot pay.
That is why mortgage rates step down in bands, commonly around 95%, 90%, 85%, 80%, 75% and 60% LTV. Moving from 90% to 85% LTV, by finding another five percent deposit, can sometimes shave a noticeable chunk off your interest rate, which compounds into real savings over a 25 or 30 year term.
It is worth checking where you sit relative to the next LTV band before you apply. Even a modest extra deposit, or a slightly lower purchase price, can tip you into cheaper pricing that outweighs the effort of saving a bit more.
Fixed, tracker and variable rates
A fixed-rate mortgage locks your interest rate for a set period, typically two, three or five years, so your payment stays the same regardless of what the Bank of England does with the base rate. This predictability is popular in the UK because it makes budgeting straightforward and protects you from sudden rate rises.
A tracker rate moves in line with the Bank of England base rate plus a fixed margin, so your payment can rise or fall each time the base rate changes. Standard variable rate, or SVR, is the lender's own default rate you usually fall onto once a fixed or tracker deal ends, and it is almost always more expensive than deals you could remortgage onto.
Choosing between them is a bet on your own risk tolerance as much as on where rates are heading. Fixes suit people who want certainty and are stretched on affordability; trackers can suit those comfortable with fluctuation who believe rates may fall.
How the mortgage term changes your payment
The term is how many years you have to repay the loan, commonly 25 years but increasingly stretched to 30 or even 35 to keep monthly payments affordable. A longer term reduces your monthly outgoing because the debt is spread over more payments, but it increases the total interest you pay over the life of the loan.
For example, a £225,000 repayment mortgage at 4.5% over 25 years costs noticeably less per month than the same loan over 20 years, but you will pay meaningfully more interest in total across the longer term. There is no universally right answer; it depends on whether your priority is monthly cash flow now or minimising lifetime cost.
Many borrowers choose a longer term for affordability at the outset and then make overpayments later, once income rises, to bring the effective payoff date forward without being locked into higher contractual payments.
Repayment versus interest-only
With a repayment mortgage, each monthly payment covers some interest and some capital, so the balance shrinks steadily and is guaranteed to hit zero at the end of the term provided you keep paying. This is now the default and most widely available option for residential borrowers in the UK.
Interest-only means you pay just the interest each month, leaving the original capital untouched, so your monthly cost is lower but you need a credible plan, savings, investments or a planned sale, to repay the full loan at the end. Lenders have tightened rules on interest-only significantly since the 2008 financial crisis and now expect proof of a repayment strategy.
Interest-only can suit specific situations such as buy-to-let, where rental income services the interest and the property itself is the exit plan, but for most homeowners a repayment mortgage remains the simpler and safer route.
What actually moves your monthly figure
Four things drive your payment: the loan amount, the interest rate, the term and the repayment type. Of these, the interest rate has an outsized effect because mortgage interest compounds; a one percentage point rate difference on a large loan can change your monthly payment by more than most people expect.
Product fees also matter more than they first appear. A deal advertising a slightly lower rate but a £999 arrangement fee is not automatically cheaper than one with a marginally higher rate and no fee once you look at the true cost over the deal period.
Running your own numbers through a mortgage calculator before you commit is one of the simplest ways to sanity-check what a broker or lender quotes you, and to compare different term and rate combinations side by side.
Fees, valuations and the real cost of switching
Beyond the headline rate, mortgages come with arrangement fees, valuation fees, and sometimes legal fees if you are remortgaging with a new lender. Some deals let you add the arrangement fee to the loan rather than paying it upfront, which is convenient but means you pay interest on the fee itself over the term.
Early repayment charges are another cost to watch. Most fixed and tracker deals carry a penalty, often a percentage of the outstanding balance, if you repay early or remortgage before the deal ends, so timing your next move around when your current deal expires matters.
When you remortgage, factor in these fees against the interest saved. A cheaper rate that costs £1,500 in fees only makes sense if the interest saving over the deal period comfortably exceeds that outlay.
Stress testing and affordability checks
UK lenders are required to check that you could still afford your mortgage if rates rose, typically stress-testing your application against a rate several percentage points above the one you are actually being offered. This protects both you and the lender from overextending into payments that only work in a best-case scenario.
Your income, existing debts, credit history and monthly outgoings such as childcare or student loan repayments all feed into how much a lender will offer you. Two people on the same salary can be offered very different amounts depending on their existing commitments.
It is sensible to run your own stress test too: work out what your payment would look like at a rate two or three points higher than today's, and check you would still be comfortable, rather than relying solely on the lender's calculation.
First-time buyer schemes worth knowing
Various UK schemes exist to help first-time buyers, including guarantor mortgages, family deposit schemes where a relative's savings back your deposit, and shared ownership, where you buy a percentage of a property and rent the rest from a housing association. Availability and rules change frequently, so check current terms directly with lenders or Homes England.
Lifetime ISAs are another route: save into one as a first-time buyer and the government adds a 25% bonus on contributions up to certain limits, which can meaningfully boost a deposit over a few years of saving.
None of these schemes remove the need to budget carefully for ongoing costs like buildings insurance, maintenance and ground rent or service charges if you are buying a leasehold flat.
Common questions
- How much deposit do I need for a UK mortgage?
- Most lenders ask for at least 5% of the property price, though rates improve substantially at 10%, 15% and 25% deposits. A larger deposit reduces your loan-to-value, which usually unlocks cheaper interest rates, so even saving a little more before you apply can be worthwhile. Figures here are general estimates, not advice for your situation.
- What is a mortgage in principle?
- A mortgage in principle, sometimes called an agreement in principle, is an estimate from a lender of how much they might lend you based on a quick check of your income and credit history. It is useful for house hunting and shows sellers you are a credible buyer, but it is not a guaranteed offer and the full application can still be declined.
- Should I choose a two-year or five-year fix?
- A shorter fix gives you flexibility to remortgage sooner if rates fall, while a longer fix gives more payment certainty and can carry a lower rate depending on market conditions at the time. There is no universally correct choice; it depends on your appetite for uncertainty and how likely your circumstances are to change within that window.
- What happens when my fixed-rate deal ends?
- Unless you remortgage or switch products beforehand, you will move onto your lender's standard variable rate, which is typically significantly more expensive. Most people arrange a new deal a few months before their current one ends to avoid ever paying the SVR, and many lenders let you lock in a new rate up to six months ahead.
- Can I overpay my mortgage without penalty?
- Most UK mortgage deals allow you to overpay up to 10% of the outstanding balance each year without triggering an early repayment charge, though this varies by lender and product, so check your specific terms. Overpaying beyond that limit, or clearing the mortgage entirely during a fixed deal, can trigger a charge, which is worth weighing against the interest saved.