The Situation: Saved Hard, Still Unsure
Priya was 29, a nurse working for an NHS trust in Manchester, earning £34,000 a year. She had spent three years saving carefully — skipping holidays, taking on bank shifts, living with her parents longer than she'd planned. By early 2024, she had £18,500 sitting in a Lifetime ISA. Her target property was a two-bedroom flat in Salford, listed at £185,000.
On paper, that looked straightforward. £18,500 on a £185,000 purchase is exactly 10%. Most people Priya spoke to — colleagues, her parents, a friend who'd bought a year earlier — told her 10% was "fine" and that she was ready to go. One colleague insisted she should wait and save a full 25% before buying anything.
Priya's real question wasn't just how much she had. It was: what does deposit size actually change, and is there a point at which saving more stops being worth it?
For first-time buyers in the UK, a deposit is typically expressed as a percentage of the property's purchase price. The minimum required by most lenders is 5%, but the rate you pay, the products available to you, and your monthly cost change significantly as that percentage rises.
What She Tried First: The 5% Route
Before Priya had accumulated her full £18,500, she had seriously considered buying sooner with a 5% deposit — roughly £9,250 on a £185,000 flat. The government's Mortgage Guarantee Scheme, which ran until June 2025, allowed lenders to offer 95% loan-to-value (LTV) mortgages with government backing, and several high-street names were participating.
The rates on offer at 95% LTV in early 2024 were sitting around 5.5% to 6.0% for a two-year fixed deal. On a £175,750 mortgage (95% of £185,000) over 25 years, that translated to a monthly repayment of roughly £1,145–£1,195.
There was also the matter of Lenders' Mortgage Insurance — though the UK doesn't charge this as a separate premium the way Australia does, the cost is effectively embedded in the higher interest rate. At 95% LTV, lenders price in their elevated risk. That's not a fee line on your mortgage offer; it's baked into every monthly payment for the entire fixed term.
Priya also looked at the Help to Buy: Equity Loan scheme — but this closed to new applications in March 2023. That door was shut. She noted it for reference, but it wasn't an option.
What gave her pause about the 5% route wasn't the monthly payment in isolation. It was the combination of: a higher rate, a longer period before she'd build meaningful equity, and the fact that any short-term fall in property values would put her in negative equity almost immediately. A £185,000 flat dropping 6% in value would wipe out her entire deposit.
What Actually Happened: The 10% Calculation
Priya waited until she had the full £18,500 — her 10% deposit — before approaching lenders. The difference in the mortgage market was measurable and immediate.
At 90% LTV, the best two-year fixed rates available to her came in around 4.7% to 4.9%. On a £166,500 mortgage (90% of £185,000) over 25 years, her monthly repayment dropped to approximately £940–£965.
That's a saving of roughly £195–£230 per month compared to the 95% LTV products — or between £4,680 and £5,520 over a two-year fixed term. Her additional savings of £9,250 had effectively "earned" her over £5,000 in reduced payments within two years alone, before any rate reset.
She also had access to a wider product range. At 95% LTV, her choice of lenders was limited to those participating in the Mortgage Guarantee Scheme. At 90%, she could access the full mainstream market — including mutuals and building societies with more flexible underwriting, which mattered because her income included some bank-shift overtime that not all lenders would count.
Her broker helped her use a Lifetime ISA withdrawal correctly: the 25% government bonus (£4,000 on her £16,000 of contributions) was included in her deposit, taking her effective deposit to £20,000 — just over 10.8%. That nudged her further into the 90% LTV tier with some cushion to cover valuation risk. This is a detail that catches many first-time buyers out: LISA bonuses count toward your deposit, but only if you've owned the account for at least 12 months and are buying a property priced at or below £450,000.
The General Lesson: What Deposit Size Really Controls
Priya's experience maps onto a set of principles that apply to most first-time buyers across the UK. Here's what deposit size actually changes:
1. Your Interest Rate — and Every Month's Payment
UK mortgage rates are tiered by LTV bands. The most significant steps are at 95%, 90%, 85%, 80%, and 75%. Crossing from one band into the next typically reduces your rate by 0.2–0.5 percentage points. The largest single jump in savings usually comes from moving from 95% to 90% LTV. After 75% LTV, the improvements become more incremental.
2. Your Lender Choice and Underwriting Flexibility
High LTV products attract fewer lenders. At 95%, you are often limited to mainstream banks participating in a guarantee scheme. At 85–90%, building societies and specialist lenders re-enter the picture, offering more nuanced income assessment — which matters for nurses on overtime, self-employed buyers seeking residential mortgages, contractors, or anyone with a non-standard employment pattern.
3. Your Equity Buffer Against Price Movements
Property values in the UK do not move in a straight line. A 5% deposit means a 5% fall in value wipes out your equity entirely. A 10% deposit gives you a modest but meaningful cushion. At 15–20%, you are much better insulated against short-term market corrections — which historically occur every 7–12 years in the UK market.
4. Your Stamp Duty Position
First-time buyers in England pay no Stamp Duty Land Tax (SDLT) on the first £425,000 of a property's value (as at 2024–25). This threshold is set to revert to £300,000 from April 2025 unless Parliament acts. Your deposit size doesn't change your SDLT liability, but it does affect how much cash you need in total — since SDLT is paid on top of your deposit from your own funds, not from the mortgage.
5. The Point at Which Waiting Longer Stops Paying
There is a break-even point beyond which additional saving delays your purchase without proportionate rate benefit. For most buyers, the step from 5% to 10% is worth the wait. The step from 10% to 15% is often worth it too. But saving from 15% to 25% while paying rent can cost you more in lost time and rising prices than the rate improvement is worth. Run the numbers on your specific property price, local market trend, and current rent — not on a rule of thumb you heard from a colleague.
Benchmarks Worth Knowing
- 5% deposit (95% LTV): Minimum for most lenders; highest rates; limited product range; maximum negative equity risk.
- 10% deposit (90% LTV): First major rate improvement; broader lender choice; widely considered the practical entry point for most first-time buyers.
- 15% deposit (85% LTV): Further rate reduction; useful for buyers with complex income needing more lender options.
- 20–25% deposit (80–75% LTV): Best mainstream rates; lowest risk; suitable if your rental cost is low and you can save quickly without market timing risk.
- Lifetime ISA: If you're under 40 and buying a property under £450,000, the 25% government bonus on up to £4,000 per year is one of the most efficient ways to boost your deposit.
Key Takeaways
- The minimum deposit in the UK is 5%, but rates and product choice improve significantly at 10%, 15%, and 25% LTV thresholds.
- Moving from 95% to 90% LTV typically saves first-time buyers £150–£250 per month on their mortgage payment — often more than £5,000 over a two-year fix.
- A Lifetime ISA bonus counts toward your deposit but requires at least 12 months of account ownership and a purchase price of £450,000 or less.
- Lender choice expands meaningfully once you move below 90% LTV, which matters most for buyers with complex income or non-standard employment.
- Waiting to save a larger deposit only makes financial sense up to a point — weigh your rent cost and local price growth against the rate saving you'd gain.
Every first-time buyer's arithmetic looks slightly different depending on property price, location, income type, and how fast their savings grow. Priya's story isn't a template — it's an illustration of the questions worth asking before you decide your number.
Working with Agnes Mortgage
Agnes Mortgage is a whole-of-market UK mortgage broker specialising in residential purchases for first-time buyers, including those with complex income, shift-pattern employment, or LISA-funded deposits. If you're working out the right deposit strategy for your situation, you can book a private consultation at /#contact — you'll speak directly with a named broker, not a call centre.
Frequently asked questions
What is the minimum deposit for a first-time buyer in the UK?
The minimum deposit accepted by most UK mortgage lenders is 5% of the property's purchase price, which means you would borrow 95% (a 95% LTV mortgage). However, rates at this level are significantly higher than at 10% or 15% deposits, and your choice of lenders is more limited.
Is a 10% deposit enough to buy a house in the UK?
Yes, a 10% deposit is sufficient for most mainstream lenders and opens up a much wider range of mortgage products than a 5% deposit. You will typically access lower interest rates at 90% LTV than at 95% LTV, often saving hundreds of pounds per month on repayments.
Does a Lifetime ISA bonus count as part of my deposit?
Yes, the 25% government bonus from a Lifetime ISA can be used as part of your deposit for a first home. The property must be priced at £450,000 or less, you must have held the LISA for at least 12 months, and you must be a first-time buyer.
How much deposit do I need for a better mortgage rate as a first-time buyer?
The most significant rate improvement for first-time buyers comes at the step from 95% to 90% LTV (5% to 10% deposit). Further improvements are available at 85%, 80%, and 75% LTV. The jump from 95% to 90% alone can reduce your monthly payment by £150–£250 on a typical UK first home.
Should I wait longer to save a bigger deposit before buying my first home?
It depends on your rent cost, local property price trends, and how quickly you can save. Moving from a 5% to a 10% deposit is almost always worth the additional saving period. Beyond 15%, the ongoing cost of renting while you save can outweigh the interest rate benefit you'd gain, especially in rising markets.