Stamp Duty Calculator

What this calculator does

This stamp duty calculator works out the SDLT payable on a residential purchase in England or Northern Ireland. Enter the purchase price and whether you are a home mover, a first-time buyer, or buying an additional property, and it returns the total duty, the effective rate as a percentage of the price, and the full cost of buying including the tax.

SDLT is progressive: each portion of the price is taxed at its own rate rather than the whole price at the top rate. That is why the effective rate shown is always lower than the headline band you fall into, and why a £450,000 purchase attracts 2.78 percent overall despite reaching the five percent band.

When to use it

Run it before you make an offer, since SDLT must be paid in cash within 14 days of completion and cannot be added to the mortgage. For many buyers it is the second largest cash requirement after the deposit.

It is most valuable around thresholds. First-time buyer relief vanishes entirely above £500,000, so a purchase at £505,000 costs £12,750 in tax against £10,000 at £500,000 — worth knowing before you bid. It is equally important for landlords: the five percent additional property surcharge applies to the whole price, so comparing the same property as a home and as a buy-to-let shows a difference that changes the investment case outright.

Understanding the inputs

Property purchase price is the agreed price. Where fixtures and fittings are being bought separately and genuinely reflect market value, they fall outside the chargeable consideration — but HMRC scrutinises inflated apportionments closely, so keep it defensible.

Buyer type drives everything. Home mover applies standard rates. First-time buyer gives relief up to £500,000, and both purchasers must qualify — prior ownership anywhere in the world by either party disqualifies both. Additional property covers a second home, a buy-to-let, or any purchase where you will own more than one residential property at the end of the day, and the surcharge applies even if the new property is intended as your main home until you sell the old one.

How is this calculated?

Stamp Duty (SDLT) is a progressive tax. Different rates apply to different portions of the property value.

A worked example

Take a £450,000 purchase. As a home mover the calculation runs in slices: nothing on the first £125,000, two percent on the £125,000 to £250,000 slice giving £2,500, and five percent on the remaining £200,000 giving £10,000. Total SDLT is £12,500, an effective rate of 2.78 percent.

The same property as a first-time buyer costs £7,500 — five percent on the £150,000 between £300,000 and £450,000 — a saving of £5,000. As an additional property it costs £35,000: the £12,500 standard duty plus a five percent surcharge of £22,500 on the full price, an effective rate of 7.78 percent. That £22,500 is capital that produces no return, and on a buy-to-let it typically wipes out two or three years of net rental profit.

Limitations and assumptions

This covers England and Northern Ireland only. Scotland's LBTT and Wales's LTT use different thresholds and different surcharge rates — Scotland's Additional Dwelling Supplement is eight percent and Wales offers no first-time buyer relief — so the figures here do not apply there.

The calculator does not handle mixed-use property charged at non-residential rates, purchases by companies subject to the fifteen percent flat charge above £500,000, non-resident surcharges of a further two percent, linked transactions, or refund claims when a previous main residence is sold within 36 months. It also excludes conveyancing, searches, survey, mortgage fees, and removals. SDLT rules change with fiscal events, so confirm current rates with your conveyancer before budgeting.