About — Stamp Duty Calculator

What this site does

Stamp Duty Calculator is a free UK property tax and affordability toolkit. We started as a Stamp Duty Land Tax (SDLT) calculator for England and Northern Ireland — covering standard, first-time buyer, additional-property and non-UK resident scenarios — and expanded from there. We now also cover affordability (how much you can borrow), the full moving costs picture, and a first-time buyer hub.

Alongside the calculator we publish a longer SDLT guide and a frequently asked questions page covering the rules, common edge cases, and the kinds of situations buyers and their solicitors run into.

How we keep the rates accurate

The calculator uses the published HMRC residential SDLT rates in force from 1 April 2025 onwards. We review the rates after every UK Budget and Spring Statement, and any time HMRC publishes a change. The current rate tables are mirrored on the calculator page and explained in detail in the guide.

Calculation logic is unit-tested against a battery of worked examples spanning every band, every buyer type, and the surcharge threshold edge cases. We track every rate change in a public changelog (see the guide for the recent history of SDLT changes).

What this site is not

We are not a regulated financial adviser, accountant, solicitor or conveyancer. The calculator gives you a guidance figure based on the headline SDLT rules; it cannot capture the full set of rules for things like mixed-use properties, shared ownership staircasing, linked transactions, transfers between connected parties, or purchases by companies and other non-natural persons. Always confirm the exact SDLT figure with your solicitor or HMRC before completing.

Contact

For corrections, feedback or partnership enquiries, email contact@dutycalculatorstamp.co.uk. We try to respond within a few working days.

Editorial standards

Every guide and calculator page on this site is written and maintained by the Stamp Duty Calculator editorial team. Our editorial standards, correction policy and review cadence are published in full on the editorial standards page. We do not use AI-generated content without editorial review; every published page has a "last reviewed" date visible at the foot of the page.

Corrections are logged, dated and published transparently. If you spot an error — a rate that has changed, a threshold that has moved, a worked example that no longer matches HMRC's published tables — email us. We will investigate within 5 working days and issue a correction if warranted.

Calculator methodology

Every calculator on the site is built on published UK government or regulator sources. The core SDLT calculator implements the residential SDLT band table currently published by HMRC. The LBTT calculator implements the Revenue Scotland residential LBTT rates. The LTT calculator implements the Welsh Revenue Authority residential rates.

For non-tax calculators (affordability, deposit, mortgage repayment, stress test) we apply the underlying financial formulas that lenders and the FCA use in mortgage conduct rules. Affordability is modelled against income-multiple bands and net-income affordability tests. Mortgage repayment uses the standard PMT amortisation formula. Stress testing applies the Bank of England's 3-percentage-point conservative uplift against current standard variable rate benchmarks.

Every calculator is regression-tested against a battery of worked examples covering every band, every threshold, and edge cases including surcharge interactions, first-time buyer relief cut-offs, and non-resident adjustments. Where a calculator uses a modelling assumption (e.g., default interest rate), that assumption is stated on the page.

Sources we cite

Our published guides cite primary UK sources. The most frequently cited include:

GOV.UK — Stamp Duty Land Tax — HMRC's official SDLT hub, including current residential rates
HM Revenue & Customs — technical manuals, published guidance notes
HM Land Registry — registration fees, title data
Financial Conduct Authority — mortgage conduct rules (MCOB)
Bank of England — UK mortgage market statistics, base rate history
MoneyHelper — the free UK impartial money guidance service
The Law Society — conveyancing protocol and practice notes
Solicitors Regulation Authority — SRA transparency rules
Council for Licensed Conveyancers — CLC fee transparency
Revenue Scotland — LBTT rates and rules
Welsh Government — LTT rates and rules

Individual pages cite additional specialist sources where relevant — Coal Authority, Environment Agency, Building Societies Association, UK Finance, the Property Ombudsman, the Legal Ombudsman, and others. Every source in a page's "Sources" list links to the primary publication.

Review and update cadence

Rate tables are reviewed after every UK Budget, Spring Statement and Autumn Statement — and any time HMRC, HM Treasury, Revenue Scotland or the Welsh Revenue Authority publishes a rate change out of cycle. Content pages are reviewed on a rolling schedule with a maximum age of 12 months since last review. Every page shows its "last reviewed" date in the footer of the main content area.

Where a page is updated for a material change (rate change, rule change, new relief), the date on the page is updated and a note is added to the corrections log. Minor typographical corrections do not usually update the date.

Who this site is for

The site is written for UK residential property buyers, sellers, and their advisers. Typical readers include first-time buyers researching SDLT for the first time; home movers modelling the cost of a chain transaction; second-home buyers wrestling with the additional-property surcharge; buy-to-let investors modelling BTL SDLT and mortgage affordability; solicitors and conveyancers double-checking calculations; and remortgagers evaluating whether switching is worth the effort.

We aim to explain in plain English what HMRC and the lenders assume you already understand. Where the rules have an edge case that catches out buyers, we call it out specifically — see the common SDLT pitfalls page for the most frequent traps.

Independence and monetisation

The site is independently produced. We are not affiliated with HMRC, the government, or any bank, lender or estate agency. We make money through display advertising and, on pages where we recommend a third-party service, through affiliate commissions. Affiliate links are labelled "(Sponsored)" and use the standard rel="sponsored" attribute. Advertisers do not influence editorial content or the calculators.

Sister sites in the same portfolio — PennywiseFinance, PayslipCheck, Freelance Toolkit UK — cover adjacent personal finance topics but operate under the same editorial standards documented on the editorial standards page.