Module 03 - Deposit Planner | First Home

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The deposit is the number most couples fixate on - and for good reason. It determines your mortgage rate, your monthly payments, and which properties you can actually buy. But the maths is simple once you lay it out clearly.

How deposits work in the UK

Your deposit is expressed as a percentage of the property price. A 10% deposit on a £250,000 property means you need £25,000. The remaining 90% is your mortgage - called a 90% Loan to Value (LTV) mortgage.

Why more deposit is almost always better: Lenders price mortgages by risk. A 10% deposit (90% LTV) comes with higher rates than a 15% deposit (85% LTV) or 20% (80% LTV). Even a small increase in deposit can drop you into a significantly cheaper mortgage bracket. Run both scenarios in the calculator below.

The minimum deposit for most residential mortgages is 5%. However, mortgages above 90% LTV come with higher rates and fewer lenders. 10–15% is often the sweet spot for first-time buyers. 20%+ unlocks the best rates.

Lifetime ISA (LISA): If either of you is under 40, you can open a LISA and get a 25% government bonus on up to £4,000 saved per year - that's up to £1,000 free money annually. The property must be your first home, priced under £450,000. This is one of the best savings tools available to first-time buyers.

Calculator

Deposit planner

Target property value£

Deposit % you're aiming for%

Current savings toward deposit£

Monthly amount you can save£

Deposit needed

£ -

Still to save

£ -

Months to target

0% of deposit saved

Scenario planning

What if we saved more?

Use this section to compare your current plan against a stretch scenario - what would happen if you increased monthly savings or targeted a higher deposit percentage?

Stretch monthly savings

Alternative deposit %

Your savings plan

Where is the money coming from?

Source	Current balance (£)	Monthly addition (£)	Notes

Are there any windfalls or large savings events expected? (bonus, inheritance, sale of asset)

Before you move on

You know exactly how much deposit you need
You can see how many months away you are at your current savings rate
You've compared your plan against a stretch scenario
You've mapped every source of deposit money
You know your LTV and what mortgage rate bracket it puts you in

Educational worksheet only. Not financial advice. The Investing Couple is a personal finance content brand. For mortgage, legal or financial advice specific to your situation, speak to a qualified adviser.