Methodology
This calculator computes SDLT, LBTT and LTT the same way for every jurisdiction: it selects the ruleset that was in effect on the transaction date, then applies exactly one of four calculation paths, in a fixed order.
How a figure is computed
- Non-residential or mixed-use property: the non-residential band schedule applies, in full, regardless of buyer type. Buyer-type reliefs (first-time buyer, additional-property) never apply to non-residential purchases.
- Additional property, not replacing a main residence: the jurisdiction's additional-property mechanism applies (a per-band surcharge, a flat rate on the whole price, or a separate band schedule — seesecond homes and buy-to-let for how these differ).
- First-time buyer, where the jurisdiction offers relief and the price is within any price cap: the first-time-buyer band schedule applies instead of the standard bands.
- Otherwise: the standard residential band schedule applies.
A non-UK-resident surcharge, where the jurisdiction has one, stacks on top of whichever of the four paths above applied — it's calculated independently, not as an alternative to them.
What's out of scope
This calculator does not model:
- Multiple Dwellings Relief (abolished for England/NI transactions from 1 June 2024).
- Linked transactions.
- Leasehold net-present-value-of-rent charges.
- The non-residential 6-or-more-dwellings election.
- Corporate, ATED-related, charity, partnership, or trust reliefs — this calculator assumes an individual buyer throughout.
- Apportionment of mixed-use prices between residential and non-residential elements — selecting "mixed-use" produces a warning rather than an apportioned figure.
For any of these, speak to a solicitor or conveyancer — see the disclaimer on every result page, or the guide to what this calculator doesn't cover for a plainer-English walkthrough of the same list.
How the rate data is verified and maintained
Every rate in this calculator is read from a single registry file per jurisdiction, structured as effective-dated rulesets. Nothing is hardcoded anywhere else in the calculation engine. Each rate was independently re-verified against its primary source rather than copied from a secondary summary — seesources for exactly which pages were checked, andthe changelog for when.