New Build Stamp Duty Calculator
Calculate stamp duty on new build properties. Understand SDLT treatment for off-plan purchases, part-exchange deals, and how builder incentives affect your tax liability.
Annexe, land or an old home not sold yet?
These are the purchases where a standard calculator can get your stamp duty wrong. Get it checked before you exchange.
Your Results
Stamp Duty to Pay
£5,000
Effective tax rate: 1.67%
Tax Breakdown
| Band | Rate | Tax |
|---|---|---|
| £0 - £125,000 | 0% | £0 |
| £125,001 - £250,000 | 2% | £2,500 |
| £250,001 - £300,000 | 5% | £2,500 |
| Total | £5,000 | |
£0 - £125,000
0%
£0
£125,001 - £250,000
2%
£2,500
£250,001 - £300,000
5%
£2,500
Total
£5,000
Tax by Band
Added to 25-Year Mortgage
£29/month
Based on 5% interest rate, added to loan amount
Understanding New Build Stamp Duty
How New Builds are Taxed
New build properties are subject to the same stamp duty rates as existing homes. There is no special relief or surcharge specifically for new builds in England. Review our residential property guide for more details.
Off-Plan Considerations
When you buy off-plan, SDLT is due at completion (when you receive the keys), not at exchange. The completion date determines which tax rates apply. Use our guide on how stamp duty is calculated to understand the banded system.
Part-Exchange Schemes
In a part-exchange you pay SDLT on the full price of the new home, not on the cash difference. The old property you hand over is non-cash consideration and counts towards the chargeable amount. On a £500,000 new build with a £300,000 part-exchange, SDLT is charged on £500,000, which is £15,000, not on the £200,000 balance. The part-exchange relief in Schedule 6A of the Finance Act 2003 belongs to the house-building company on its acquisition of your old home, subject to conditions, not to you.
New Build Stamp Duty Examples
| Property Price | SDLT (Standard) | SDLT (FTB) | SDLT (Additional) | Effective Rate |
|---|---|---|---|---|
| £250,000 | £2,500 | £0 | £15,000 | 1.0% |
| £400,000 | £10,000 | £5,000 | £30,000 | 2.5% |
| £500,000 | £15,000 | £10,000 | £40,000 | 3.0% |
| £750,000 | £27,500 | N/A | £65,000 | 3.7% |
FTB = First-Time Buyer (up to £500k). Additional = Additional dwelling surcharge (5%).
Special Considerations for New Builds
Completion Date is Tax Point
SDLT is calculated using the rates in force at the effective date, which is the completion date, or the date of substantial performance if you take possession earlier. It is not the date you exchanged contracts. If rates change between exchange and completion, the new rates apply.
- •Plan for potential rate changes
- •Budget conservatively if long build time
- •Monitor HMRC announcements
Builder Incentives and the Price
Whether an incentive reduces your SDLT depends on what it is. A just and reasonable apportionment to moveable items such as white goods, carpets and curtains reduces the chargeable consideration. Fixtures that form part of the property, like a fitted kitchen, do not. Cash contributions towards your deposit, legal fees or stamp duty are the contested case and HMRC often treats the full contract price as consideration.
- •Moveable chattels can be apportioned out, fixtures cannot
- •Get developer confirmation in writing
- •Include in SDLT return accurately
Ground Rent Implications
For leasehold new builds with ground rent, if the NPV of ground rent exceeds thresholds, it can affect SDLT. Most modern leases have low ground rents, minimizing impact.
- •Check NPV calculation in lease
- •Low ground rents usually have minimal effect
- •Solicitor will calculate if applicable
Warranties Don't Affect SDLT
New build warranties (NHBC, Premier Guarantee, etc.) are separate from the property purchase and do not form part of the consideration for SDLT purposes.
- •Warranty costs not included in SDLT
- •Service charges are separate ongoing costs
- •Only purchase price triggers SDLT
Important: Developer SDLT Contributions
If the developer contributes to your stamp duty bill, do not assume the contribution reduces the price for SDLT purposes. HMRC takes a narrow view here, and where the contract price is unchanged and the developer simply pays an amount on your behalf, the full contract price is usually the chargeable consideration.
Worked example: on a £300,000 property the SDLT is £5,000. If the developer pays that £5,000 for you but the contract price stays at £300,000, expect to be charged on £300,000. If instead the price is genuinely reduced to £295,000, the SDLT is £4,750. The distinction is how the contract is written, not what the money is called, so clarify the structure with your conveyancer before you exchange.
Frequently Asked Questions
Is there a stamp duty exemption for new builds?
No, there is no SDLT exemption specifically for new-build properties. You pay the same stamp duty rates as on any other residential purchase. However, developer incentives such as furniture packages or deposit contributions can reduce the effective purchase price on which SDLT is calculated.
How does part-exchange work for SDLT purposes?
In a part-exchange, the developer buys your existing home and you purchase the new build. You pay SDLT on the full price of the new home, not on the net difference, because the old property you hand over is non-cash consideration and counts towards the chargeable amount. On a £500,000 new build with a £300,000 part-exchange, SDLT is charged on £500,000, which is £15,000, not on the £200,000 balance. The part-exchange relief goes to the house-building company on its purchase of your old home, not to you. If the new home is an additional property at completion, the 5% surcharge applies but can be reclaimed if your old home sells within 36 months.
Do developer incentives reduce my stamp duty?
It depends on the type of incentive and how the deal is structured, and this is an area where HMRC takes a narrow view. A genuine reduction in the price you actually pay reduces the chargeable consideration and so reduces your SDLT. Moveable chattels are treated separately: a just and reasonable apportionment of the price to items such as white goods, carpets and curtains reduces the chargeable consideration, while fixtures that form part of the property, such as a fitted kitchen or an integrated appliance, do not. Cash contributions where the contract price stays the same and the developer instead pays your deposit, your legal fees or your stamp duty are the contested case, and HMRC will often treat the full contract price as the consideration. Get any apportionment agreed in writing, keep evidence of how it was arrived at, and take advice before assuming an incentive has reduced your bill.
When do I pay SDLT on an off-plan purchase?
SDLT is due within 14 days of legal completion, not when you exchange contracts or reserve the property. For off-plan purchases, this means you do not pay SDLT until the property is built and you complete the purchase, which could be months or years after exchange.
Can first-time buyers get relief on new builds?
Yes. First-time buyer relief applies to new-build properties on the same basis as existing homes. You pay 0% on the first £300,000 and 5% on the portion between £300,001 and £500,000, provided the total price does not exceed £500,000.
Reviewed by
Julie White
ACASDLT Expert since 1999Stamp Duty Land Tax Specialist
ACA and Tax Adviser with a career spanning nearly four decades, specialising in SDLT planning and advisory work since 1999.