Commercial Stamp Duty Calculator 2025–26: SDLT on Non-Residential Property

Commercial SDLT calculator

Commercial SDLT vs residential SDLT

Commercial SDLT applies to non-residential land and property, including shops, offices, warehouses, factories, development land, forests, agricultural land used as part of a working farm, and property that is not suitable for residential occupation.

Residential SDLT applies to dwellings and their garden or grounds. The distinction matters because residential rates, additional dwelling rates and company rates can be materially higher than the non-residential schedule.

Commercial SDLT also applies to most mixed-use property. A mixed-use asset is not taxed by splitting the residential and non-residential parts into two calculations unless specific transaction structuring creates separate chargeable interests. In most ordinary purchases, the whole consideration is taxed using the non-residential and mixed-use rates.

What counts as commercial or non-residential property?

Commercial property includes offices, shops, restaurants, warehouses, industrial units, hotels, care homes, development land and other land that is not part of a dwelling's garden or grounds. A building that cannot be used as a dwelling may also be non-residential even if it once had residential features.

A transaction involving six or more dwellings can be treated as non-residential for SDLT. This is often relevant to portfolio acquisitions, block purchases and some build-to-rent structures.

The classification must be supported by the facts at completion. Planning use, physical layout, separate access, actual occupation, lease terms and the state of the building can all matter.

Mixed-use property: the tax point investors should not miss

Mixed-use property has both residential and non-residential elements. A classic example is a shop with a flat above. Other examples include a pub with living accommodation, a doctor's surgery with a self-contained flat, farmland sold with a cottage, or a commercial yard with a dwelling included in the same purchase.

Mixed-use treatment can reduce SDLT because the non-residential bands replace the residential bands. The saving is small for some standard residential comparisons, but very large where the buyer would otherwise pay higher residential rates, the non-resident surcharge or company rates.

The key risk is over-claiming. HMRC can challenge transactions where the commercial element is artificial, trivial or not genuinely part of the land being acquired. Treat mixed-use classification as a legal issue, not just a calculator toggle.

Worked example: £300,000 commercial property

A buyer purchases a freehold office for £300,000. The SDLT is calculated by taxing each slice of the price, not the whole price at 5%.

The first £150,000 is taxed at 0%, giving £0. The next £100,000 is taxed at 2%, giving £2,000. The remaining £50,000 is taxed at 5%, giving £2,500. The total commercial SDLT is £4,500.

Worked example: £600,000 mixed-use purchase vs residential SDLT

A £600,000 mixed-use purchase is charged using the non-residential rates: 0% on £150,000, 2% on £100,000 and 5% on £350,000. Total SDLT is £19,500.

The same £600,000 purchase as a standard residential purchase would produce £20,000 of SDLT. That is only a £500 saving. The important comparison is the higher-rate scenario: if the buyer would otherwise pay additional-dwelling residential rates, the residential SDLT would be £50,000, making the mixed-use saving £30,500.

For companies, non-resident buyers and portfolio investors, the classification can therefore be central to the economics of the acquisition.

Leasehold commercial SDLT and NPV

Commercial leases have a second layer that freehold purchases do not: SDLT can be charged on the net present value of the rent. For a new non-residential or mixed-use lease, calculate SDLT on the lease premium using the commercial purchase bands, then calculate SDLT on the NPV of rent using the leasehold rent bands, then add the two results.

No SDLT is payable on rent NPV up to £150,000. The portion from £150,001 to £5 million is charged at 1%, and the portion above £5 million is charged at 2%. For an assigned existing lease, SDLT normally applies to the premium or consideration only, not a fresh NPV calculation.

VAT can affect the NPV calculation where rent is VATable. Rent reviews, turnover rents and uncertain rents can require estimates and later recalculations.

Who pays commercial SDLT and when?

The purchaser or tenant acquiring the chargeable interest is responsible for filing the SDLT return and paying the tax. In most transactions, the buyer's solicitor handles the return, but that does not remove the buyer's responsibility.

For current transactions, the SDLT return and payment are normally due within 14 days of the effective date. The effective date is usually completion, but can be earlier where the contract is substantially performed. The old 30-day deadline is only relevant for historic transactions and some specialist further-return situations.

What the commercial calculator should show

A useful commercial SDLT calculator should not stop at a single tax number. It should show the band-by-band calculation, identify whether the transaction is freehold, an assigned lease or a new lease, and show lease premium tax separately from rent NPV tax.

It should also warn when the user selects mixed-use, six or more dwellings, linked transactions, uncertain consideration, VATable rent or Scotland/Wales. Those are not edge cases for commercial investors; they are the transactions where professional advice most often changes the result.