Can You Add Stamp Duty to Your Mortgage?
Most lenders will not allow you to include SDLT in your mortgage loan. But there is a common workaround — and a significant hidden cost you should understand before using it.
Key Takeaways
- •The vast majority of UK mortgage lenders do not allow SDLT to be added to the loan
- •The workaround is to reduce your deposit and use the freed cash for SDLT — but this raises your LTV
- •Borrowing £10,000 at 5.5% over 25 years costs approximately £18,423 in total — 84% more than the original
- •Moving from 85% to 90% LTV adds roughly £100–£200/month to your mortgage repayments
- •Personal loans are an alternative, but at higher rates and they affect affordability calculations
In this article
Can You Actually Add SDLT to a Mortgage?
Technically, there is no legal rule preventing a lender from including SDLT in the mortgage amount. In practice, however, the overwhelming majority of mainstream UK lenders — including all major high street banks and most building societies — refuse to do so. Their underwriting policies require that the mortgage does not exceed the property's purchase price, and SDLT is a government tax, not part of the purchase price.
Some lenders may consider borrowing above the purchase price in exceptional circumstances, but this typically requires significant equity in the property, a very low LTV, and would still result in lending against an inflated loan amount that most lenders' standard product ranges do not accommodate.
Bottom line: Do not assume you can include SDLT in your mortgage when budgeting for a property purchase. Plan to fund it entirely from your own savings or a separate borrowing arrangement.
Why Most Lenders Refuse
Mortgage lending is secured against the property. The lender needs confidence that in a forced sale scenario, they can recover the full loan amount. If a borrower defaults immediately after purchase, the lender needs to sell the property for enough to cover outstanding debt. Including SDLT in the mortgage would mean the loan is larger than the property's purchase price — a position lenders describe as starting "underwater."
There are additional regulatory considerations. The Mortgage Credit Directive and FCA rules on responsible lending require lenders to assess the purpose and security for every component of a loan. SDLT has no collateral value — it cannot be recouped from a property sale — so adding it to a secured mortgage introduces an unsecured element that contradicts the nature of the product.
Some mortgage brokers may suggest "creative" approaches to funding SDLT through the mortgage. Always confirm any approach with your solicitor and ensure your mortgage application accurately reflects how the deposit and SDLT will be funded.
The Deposit-Reduction Workaround
The most common approach buyers take when they cannot fund SDLT separately is to reduce their deposit. Here is how it works in practice:
Worked Example: £350,000 Property
In this example, the buyer reduces their deposit from £42,500 to £35,000, freeing up £7,500 to pay SDLT. The trade-off is that their LTV increases from 87.9% to 90% — moving them into a higher rate tier. This is not "adding SDLT to the mortgage" in the formal sense, but it achieves a similar effect: the buyer is borrowing more relative to the property value, and the SDLT cost is indirectly embedded in the higher interest rate they pay over the mortgage term.
LTV threshold warning: Moving from 85% to 90% LTV can add £100–£200 per month to repayments and cost tens of thousands more over the mortgage term. Always model the full 25-year cost before deciding this approach is worthwhile. See our deposit vs stamp duty guide for a full decision framework.
The True Long-Term Cost of Financing SDLT
To understand the real cost, consider a standard scenario: a buyer needs to finance £10,000 of SDLT by reducing their deposit (effectively borrowing an extra £10,000 on the mortgage). At 5.5% over 25 years:
| Financing Method | SDLT Amount | Rate | Term | Monthly Extra | Total Cost | Extra Paid |
|---|---|---|---|---|---|---|
| Pay cash | £10,000 | — | — | £0 | £10,000 | — |
| Mortgage (5.5%, 25yr) | £10,000 | 5.5% | 25 years | ~£61 | £18,423 | +£8,423 (84%) |
| Personal loan (8%, 3yr) | £10,000 | 8% | 3 years | ~£313 | £11,271 | +£1,271 (13%) |
| Personal loan (10%, 5yr) | £10,000 | 10% | 5 years | ~£212 | £12,748 | +£2,748 (27%) |
The key insight is counter-intuitive: despite carrying a much higher interest rate, a personal loan often costs less in total than spreading the SDLT amount over a 25-year mortgage. A 3-year personal loan at 8% adds just £1,271 in interest, versus £8,423 through the mortgage. This is because compounding works against you far more severely over 25 years than over 3 years, even at a lower rate.
Interactive Cost Calculator
Compare the total cost of financing your stamp duty through a mortgage vs a personal loan.
Via Mortgage (deposit reduction)
Via Personal Loan
Result: The personal loan saves £7,142 in total interest compared to adding it to the mortgage, despite the higher rate. Shorter terms beat longer terms even at higher rates.
Alternatives to Financing Stamp Duty
Pay from savings (best option)
If you have the funds, paying SDLT from savings is always cheapest. It avoids interest entirely and keeps your LTV at the level you planned.
Short-term personal loan
A 2–3 year personal loan at a competitive rate (currently 6–10% for good credit) is often cheaper than spreading the cost over 25 mortgage years. Note: lenders will factor this monthly obligation into your affordability assessment — disclose it fully.
Gift from family
A monetary gift specifically for stamp duty is entirely legitimate. Parents or relatives can gift money toward SDLT with no impact on your tax position, provided they do not appear on the title deed. See our gifted deposit guide for lender requirements.
Negotiate a lower purchase price
In a buyer's market, asking the seller to reduce the price by the SDLT amount achieves the same effect as having the SDLT covered, without any borrowing. Sellers in motivated circumstances may accept this trade-off, particularly if it keeps the transaction moving.
Delay the purchase and save
If none of the above are viable, delaying a purchase by 6–12 months to build a proper SDLT fund is always preferable to taking on expensive borrowing. Use our offset mortgage strategy guide to grow your savings tax-efficiently in the meantime.
Frequently Asked Questions
Is it better to add stamp duty to your mortgage or pay in cash?
Always pay cash if you have it. Borrowing £10,000 at 5.5% over 25 years costs approximately £18,423 in total — 84% more than the original. Even if you are confident you will remortgage before the end of the term, the interest compounds against you every month. Pay SDLT from savings, keep your LTV as low as possible, and benefit from better rates throughout the mortgage term.
How much more would I pay monthly if I borrow stamp duty?
Using the mortgage route: adding £10,000 at 5.5% over 25 years adds approximately £61 per month. However, the larger hidden cost is the LTV increase. Moving from 85% to 90% LTV on a £300,000 mortgage could add £100–£200 per month to your repayments through a higher product rate — far exceeding the marginal £61 from the SDLT amount itself.
Do all lenders allow stamp duty to be added to the mortgage?
No. The vast majority do not. High street lenders — including the major banks and most building societies — require that the mortgage amount does not exceed the property's purchase price. SDLT is not part of the price. If a broker tells you a lender will accommodate this, ask to see the specific policy in writing, and have your solicitor review the arrangements before exchanging contracts.
Ready to see your numbers?
Use our free calculator to see exactly how much stamp duty you need to budget for.
Calculate your stamp duty
Emma Richardson, MRICS
Chartered Surveyor & Property Tax Specialist
Emma Richardson is a RICS-qualified Chartered Surveyor with over 12 years of experience in UK property taxation. She founded Stamp Duty Calculator to help buyers understand the complex world of property transaction taxes.