What is StampDutyPlanner?
StampDutyPlanner is a free, independent online tool that calculates Stamp Duty Land Tax (SDLT) for residential property purchases in England and Northern Ireland. We cover all buyer types — standard home movers, first-time buyers with SDLT relief, and additional property purchases including buy-to-let investments — and we update our rates promptly whenever HMRC changes the rules.
The April 2025 changes were significant: the temporary nil-rate band of £250,000 that applied from September 2022 expired on 31 March 2025, reverting to £125,000 for standard purchases. Many buyers were caught out by the change — we built StampDutyPlanner to make it easy to calculate the correct figure under the current rules.
How accurate are the calculations?
Our calculator uses the official HMRC SDLT bands and rates as published from 1 April 2025. Stamp duty is calculated on a marginal band basis — like income tax — meaning you pay each rate only on the portion of the purchase price that falls within that band, not on the entire price. Our band-by-band breakdown shows exactly how each pound of your purchase price is taxed.
For first-time buyers, we apply the correct relief threshold of £425,000 (0% up to this amount, 5% on £425,001 to £625,000). For properties above £625,000, we correctly revert to standard rates for the entire purchase price — a common source of confusion that other calculators sometimes get wrong.
For additional properties, we apply the 5% surcharge that has been in effect since 31 October 2024 — up from 3% previously. The effective additional property rates (5%, 7%, 10%, 15%, 17%) are applied band by band, not as a flat addition to the final figure.
What does this tool not cover?
Scotland and Wales — Scotland uses Land and Buildings Transaction Tax (LBTT) and Wales uses Land Transaction Tax (LTT). Both have different rates and thresholds. This calculator covers England and Northern Ireland only.
Non-residential property — commercial properties, mixed-use properties, and land purchases have different SDLT rate structures not covered here.
Complex reliefs — multiple dwellings relief (MDR), first-time buyer relief for shared ownership, and other specialist reliefs are not modelled. Consult your solicitor if these may apply to your purchase.
Who built this?
StampDutyPlanner is an independent public resource. We are not a solicitor, conveyancer, estate agent, or mortgage broker. We do not earn referral fees from any property or financial services. The site is funded solely by advertising displayed on the page.
Is this legal or financial advice?
No. StampDutyPlanner is an estimation and information tool. Nothing on this site constitutes legal, tax, or financial advice. Your actual SDLT liability should be confirmed with your conveyancing solicitor, who will calculate and submit the return on your behalf within 14 days of completion.
Ready to calculate? Head back to the stamp duty calculator to get your instant SDLT estimate with a full band-by-band breakdown.