Mortgage and Stamp Duty Calculator UK 2025/26

Reviewed by Mustafa Bilgic
UK Calculator Editor · Updated May 2026

Five SDLT scenarios on a single residential transaction

Stamp Duty Land Tax in England and Northern Ireland in 2025/26 has five distinct treatments depending on who is buying and what they already own. The same property at the same price can attract a wildly different bill depending on which box you tick.

• Owner-occupier — replacing your main residence. Standard 0/5/10/12% bands apply.
• First-time buyer — never previously owned a residential property anywhere in the world. Pay 0% up to £425,000 then 5% to £625,000. No relief above £625,000.
• Additional dwelling — buying a buy-to-let, holiday home or second home while you already own one. Standard rates plus a flat 5% on the whole price (rate raised from 3% in October 2024 and again confirmed for the April 2026 cycle).
• Non-UK resident — anyone who has spent fewer than 183 days in the UK in the 12 months before completion. Standard rates plus a flat 2%.
• Non-UK resident additional dwelling — the worst case: standard plus 5% plus 2% — a 7% premium on the entire price.

Mortgage availability differs by buyer type too

Lenders price additional-dwelling and non-resident purchases differently from owner-occupier loans. The maximum LTV for a buy-to-let is typically 75% (some lenders 80%), against 95% for an owner-occupier first-time buyer. Non-resident lending caps at 70–75% LTV with a small group of specialist lenders only.

Rates also rise with surcharge category. A 75% LTV BTL fixed rate at April 2026 is around 5.0–5.5%, against 4.4–4.6% for an equivalent owner-occupier 5-year fix.

Owner-occupier £400,000

SDLT: 0% on £250k + 5% on £150k = £7,500. With a £60,000 deposit and 4.5% over 25 years on £340,000 → £1,890/month. Cash on completion: £67,500 (excluding solicitor and survey).

First-time buyer £400,000

SDLT: £0 (price below the £425,000 FTB threshold). Same £340,000 mortgage at 4.5%/25 → £1,890/month. Cash on completion: £60,000.

Second home £400,000 in 2026

SDLT: standard £7,500 plus 5% surcharge on the full £400,000 = £20,000 → total £27,500. The same £340,000 BTL mortgage typically prices at 5.2% over 25 years → £2,025/month. Cash on completion: £87,500.

Common mistakes to avoid

• Forgetting that the additional-dwelling 5% applies on the whole price, not just the slice above £250k.
• Believing 'I lived in the UK once' qualifies for resident status — HMRC tests the 183-day window before completion.
• Selecting first-time buyer relief on a property above £625,000 — the relief disappears completely, not just partially.
• Assuming a transfer between spouses does not trigger the additional-dwelling surcharge — it can if the receiving spouse already owns a home.
• Treating Scotland or Wales as if SDLT applied — they have their own LBTT/LTT regimes.

When to use this calculator

Use this calculator before submitting an offer if your situation is unusual (non-resident, additional dwelling, joint purchase with mixed FTB status). Run scenarios with and without the surcharge to estimate the cost of restructuring, e.g. selling an existing property before completion to escape the surcharge.

How this differs in Scotland, Wales and Northern Ireland

Owner-occupier, additional dwelling and non-resident surcharges shown here are SDLT rules in England and Northern Ireland. Scotland's LBTT system has its own 8% Additional Dwelling Supplement (ADS), and Wales has a 5% surcharge on the LTT system. The 2% non-resident surcharge applies in England/NI only — Scotland and Wales do not currently surcharge non-residents.

When this calculator is and isn't the right tool

The Mortgage and Stamp Duty Calculator UK 2025/26 above is built for the most common UK 2025/26 scenarios in this tax area. It will be the right tool when your situation maps cleanly onto the inputs — single property or simple aggregation, standard HMRC rates and bands, and individual taxpayer (rather than complex trust or partnership structures). It is informational and does not replace tailored advice from a chartered tax adviser, especially for transactions above £500,000, cross-border situations, or where reliefs interact with each other. For year-end filings, always reconcile with HMRC's own free calculators on gov.uk before pressing submit on Self Assessment.

Closely related calculators

• Mortgage Stamp Duty Calculator 2025/26 — useful when you need a different angle on the same UK property tax topic, especially if your situation involves multiple types of property income or disposal.
• Non-UK Resident SDLT Calculator — useful when you need a different angle on the same UK property tax topic, especially if your situation involves multiple types of property income or disposal.
• Second Home SDLT Calculator 2026 — useful when you need a different angle on the same UK property tax topic, especially if your situation involves multiple types of property income or disposal.
• Additional Property SDLT Calculator — useful when you need a different angle on the same UK property tax topic, especially if your situation involves multiple types of property income or disposal.
• First-Time Buyer SDLT — useful when you need a different angle on the same UK property tax topic, especially if your situation involves multiple types of property income or disposal.

Glossary of UK property tax terms

SDLT

Stamp Duty Land Tax — the UK government tax on residential property purchases in England and Northern Ireland.

HRAD

Higher Rates for Additional Dwellings — the formal name for the 5% surcharge on second homes and BTL purchases.

SDLT1

The HMRC return form filed within 14 days of completion to declare and pay SDLT.

Sliced bands

SDLT is charged on slices of the price within each band, not on the whole price at the highest band.

Effective rate

Total SDLT divided by the purchase price, expressed as a percentage.

Section 24

The 2017 rule replacing full mortgage interest deduction with a 20% tax credit for individual residential landlords.

SA105

The Self Assessment supplementary form for UK property income.

Box 44

The SA105 box for residential property finance costs (mortgage interest).

Property allowance

£1,000 tax-free band for individual property income, claimable instead of expenses.

Rent-a-Room scheme

Separate £7,500 allowance for letting a furnished room in your main home.

Tax planning checklist

1. Confirm the figures input above match your actual position — purchase contract, mortgage offer or completion statement.
2. Cross-check the year (2025/26) — figures change every April. The tax year 2026/27 starts 6 April 2026.
3. Use HMRC's official calculator at gov.uk for the final filing figure; this calculator is informational.
4. Keep records for at least 6 years — HMRC's normal enquiry window. 21 years for fraud investigations.
5. Discuss any unusual transaction (joint purchase, gift, divorce settlement, trust) with a qualified tax adviser.
6. Submit your return online via Government Gateway — paper deadlines are earlier and penalties harsher.