UK Lease Option Agreement Calculator

UK figures as of 21 June 2026 (2026/27 tax year)

Model a lease option end to end: the monthly cash flow while you control the property, the equity you capture if you exercise the option to buy at today's agreed price, and your total profit and return on the cash you actually put in. A lease option is the right - not the obligation - to buy later, so the calculator also shows what happens if you simply walk away.

The option

£
£
£
yrs

Monthly position

£
£
£

Exercise (buying at the end)

%
£
£

Total profit if you exercise

£41,984
£350/mo cash flow + equity on exercise
Stacks up - positive monthly cash flow during the term, plus equity to capture if you exercise the option.

While you control it

Monthly cash flow£350
Annual cash flow£4,200
Cash flow over 5 yrs£21,000
Built-in equity today£10,000
Cash-on-cash (annual)84.00%

If you exercise the option

Projected value (after 5 yrs)£185,484
Equity vs agreed price£35,484
SDLT on exercise£8,000
Buying + SDLT costs£9,500
Total profit (exercise)£41,984

If you walk away

Profit from cash flow only£16,000
A lease option is the right, not the obligation, to buy. If the market hasn't moved, you can simply not exercise and walk away — your downside is the cash you put in plus any improvement spend.
Get a PDF of this lease option agreement calculator

Your results are right here on the page — free, no sign-up. Add your name and email and we’ll open a clean, printable PDF of this page (choose “Save as PDF”).

What a lease option is

A lease option combines two agreements: a lease that lets you control and rent out a property, and an option that gives you the right to buy it at a price agreed today, at any point within an agreed term. You pay the owner a (often small) option fee up front and a monthly payment - usually enough to cover their mortgage - and you keep the difference between that and the rent you collect. If values rise, you can exercise and buy at the old, lower price; if they do not, you can walk away.

How the calculator works

  • Monthly cash flow = rent you collect - the payment to the owner - your running costs.
  • Built-in equity today = current market value - the agreed purchase price (your day-one margin if you bought now).
  • Projected value applies your assumed annual growth across the option term.
  • Equity on exercise = projected value - agreed price; subtract SDLT (with the 5% surcharge if it is an additional property) and buying fees for the net.
  • Total profit if you exercise = cash flow over the term + equity captured - costs - the cash you put in.

Worked example - 5-year option

Agreed price £150,000; worth £160,000 now (so £10,000 built in); £5,000 option fee.

Rent £1,100/mo, pay the owner £600, costs £150 - that is £350/mo, about £21,000 over five years.

At 3% growth the property reaches about £185,500; exercising captures roughly £35,500 of equity before about £9,500 of SDLT and fees - total profit around £42,000 on £5,000 in.

Why investors use lease options

The appeal is control with very little capital: you profit from the rent and any growth without needing a deposit or a mortgage at the outset, and you lock tomorrow's purchase at today's price. They suit motivated sellers - someone in negative equity, a tired landlord, or a property that will not sell - where a conventional purchase does not work. The trade-off is complexity and risk: the agreement must be drafted properly by a solicitor, the seller's lender position and any restrictions must be checked, and you carry the running risk during the term.

The risks to weigh

  • Title and lender: the owner's mortgage may restrict an option - this must be checked legally before you commit.
  • Negative cash flow: if rent does not cover the payment plus costs, the deal bleeds money every month.
  • Stalled growth: if values do not rise, the equity you were counting on may not appear - though you can choose not to exercise.
  • Always use a specialist property solicitor; a lease option is a legal contract, not a handshake.

This tool is a planning aid, not legal or financial advice. Lease options are nuanced - take professional advice and have every agreement drafted and reviewed by a solicitor.

Frequently asked questions

Do I pay Stamp Duty on a lease option?
SDLT is generally due when you exercise the option and complete the purchase, calculated on the agreed price (plus the 5% surcharge if it is an additional property). There can be SDLT consequences on the grant of the option or on rent in some structures, so take advice - this calculator applies SDLT on the agreed price at exercise.
What happens if the property has not gone up in value?
An option is a right, not an obligation. If exercising no longer makes sense, you can let the option lapse and walk away - your loss is limited to the cash you put in (the option fee and any improvement spend), not the price of the property.
Is a lease option the same as rent-to-rent?
No. Rent-to-rent is purely about renting a property and subletting it for a margin, with no right to buy. A lease option adds the right to purchase later at a fixed price, so you also benefit from any capital growth.
Are lease options legal in the UK?
Yes, when structured and documented correctly. They are legal contracts and must be drafted by a solicitor, with the owner's lender position and the title checked. Poorly documented options cause serious problems, so never rely on a template.

Related calculators

Important: BrickCrunch provides general information and estimates only — this is not financial, tax, mortgage or legal advice. Calculations are simplified and your circumstances may differ. UK tax and rate figures are checked against gov.uk (21 June 2026 (2026/27 tax year)) but rates change and errors are possible. Always confirm figures with gov.uk or a qualified professional before making decisions.