What a mortgage deposit actually is

A mortgage deposit is the portion of the property price you pay yourself, in cash, before the lender provides the rest. Buy a £250,000 home with a £25,000 deposit and you borrow £225,000. That borrowing is expressed as a loan-to-value ratio, or LTV — here, 90%. Almost everything about your mortgage, from the rate you're offered to how much the lender will let you borrow, comes back to that number.

Your deposit also has to be demonstrably yours. Expect to provide bank statements covering the last three to six months, and a letter from anyone gifting you money confirming it's a gift rather than a loan, and that they won't claim an interest in the property.

How much deposit do you need?

The minimum is usually 5% of the purchase price. On a £250,000 property that's £12,500; on £180,000 it's £9,000. A few lenders go lower on specific schemes, but 5% is the realistic floor for most buyers.

Minimum isn't typical, though. First-time buyers in the UK put down around £60,000 on average — considerably less in parts of the North East and Scotland, far more in London. Averages aren't targets, but they show that plenty of buyers decide a larger deposit is worth waiting for.

The ladder broadly looks like this:

• 5% (95% LTV) — widest access, highest rates, tightest affordability checks.
• 10% (90% LTV) — the first meaningful drop in cost.
• 15% (85% LTV) — fewer lenders, noticeably better pricing.
• 20% (80% LTV) — the sweet spot most brokers aim for; most of the market competes here.
• 25% or more — the cheapest rates, though gains flatten beyond this point.

Why a bigger deposit saves you twice

First, the rate. Price a £200,000 mortgage over 30 years and the gap between 95% and 80% LTV can be roughly one percentage point. At 5.5% you'd repay about £1,135 a month; at 4.5%, closer to £1,013. That's around £120 a month, or £1,400 a year, for the same house.

Second, the loan itself. Borrow £225,000 rather than £200,000 and you're paying interest on an extra £25,000 for decades. There's no clever way around that arithmetic.

There's a quieter benefit too: lenders stress-test your finances against higher rates. The smaller the loan relative to the property's value, the more comfortably you pass, and the more they'll be willing to lend.

Where first-time buyer deposits come from

• Your own savings — the cleanest option and the easiest to evidence.
• A Lifetime ISA — a government-backed account that adds a 25% bonus to what you pay in, up to £1,000 a year, towards a first home worth up to £450,000. You must be 18 to 39 to open one, and it needs to have been open at least 12 months before you use it.
• A gifted deposit — usually from parents or grandparents. Perfectly normal, but the paperwork matters: the donor should confirm in writing that it's a gift with nothing expected back.
• Sale proceeds — money from an inherited property, for example, counts.

What lenders won't accept is a deposit that's borrowed — a personal loan, an overdraft or a credit card. It defeats the purpose of a deposit and will show on your credit file.

The costs that sit alongside your deposit

Save for the deposit alone and you'll be caught short. Budget separately for a solicitor or conveyancer (£1,000–£2,000 including searches), a valuation (£250–£500, sometimes waived as part of a deal), a survey (£400–£800), a product fee (£0–£1,000 or so), and removals, furniture and any immediate repairs.

In England and Northern Ireland, first-time buyer Stamp Duty relief may apply, though thresholds have changed in recent years, so check the current rules rather than relying on memory. Scotland and Wales have their own property taxes and their own first-time buyer rules.

Practical steps to build your deposit faster

Set a target and a monthly figure, then work backwards. Needing £25,000 at £500 a month takes a little over four years, less with interest or a bonus along the way.

• Keep the deposit out of your current account. A separate savings account, ideally a regular saver, makes it harder to spend and easier to evidence.
• Use your allowances. A Lifetime ISA for the first home, plus a cash ISA for anything above the bonus-eligible limit.
• Attack the biggest outgoings. Renegotiating rent, insurance or broadband usually beats trimming small treats.
• Clear small debts before applying. Card balances reduce what a lender will offer, even if you're saving diligently.
• Hold back a buffer. Keep a few thousand after completion — a boiler failing in month two is far less frightening with money set aside.

Don't assume you must wait for a 20% deposit. Five per cent gets you on the ladder, and you can remortgage into a better rate as your equity builds. If a larger deposit is genuinely within reach, waiting a little usually pays off — as long as the wait doesn't cost you more than it saves.