Can I add stamp duty to my mortgage?
Not directly, the lender pays the seller, not HMRC. But you can borrow more against the property if affordability allows, then use the additional cash to cover SDLT. The maths and the catches matter.
Last reviewed 16 May 2026.
Why "adding SDLT to the mortgage" is a slight misnomer
A mortgage advance is paid by the lender to the seller's conveyancer at completion. It does not flow through your account. There is no mechanism for the lender to send a separate cheque to HMRC. So you cannot literally pay SDLT from the mortgage.
What you can do is borrow more than the strict purchase price minus deposit, using the surplus to cover SDLT, fees, and other moving costs. The lender still pays the seller the full purchase price; the extra cash arrives in your account beforehand or is netted off via the conveyancer.
The two routes
Borrowing a higher loan-to-value
If you have £40,000 saved and your purchase is £300,000, you might plan a 90% LTV mortgage of £260,000 and a £40,000 deposit (plus pay SDLT separately). Alternatively, you could keep more cash aside for SDLT by borrowing at a higher LTV (say 95%) and using a smaller deposit. The surplus from your savings then funds SDLT.
This works for first-time buyers with very small deposits but has two real costs: a higher LTV typically comes with a higher interest rate, and you pay interest on the larger balance for the life of the mortgage.
Releasing equity on a remortgage
If you already own and are remortgaging, for example, to buy a second home, you may be able to release equity from your existing property to cover SDLT on the new one. This is common with buy-to-let portfolio expansion. It requires affordability evidence and reduces the equity cushion in your existing property.
The real cost of borrowing SDLT
Adding £10,000 of SDLT to a £250,000 mortgage at 5% over 25 years adds roughly £58 to monthly payments and about £7,500 in total interest over the term. It can be the right call when cash is tight, but the total cost is materially higher than paying SDLT from savings.
Is SDLT tax-deductible?
No, SDLT is a capital cost, not a revenue expense. You cannot deduct it from rental income for income tax. For a buy-to-let, the SDLT paid is added to the property's acquisition cost for capital gains tax when you eventually sell, it reduces the gain by the amount you paid, so you eventually get some of it back through a lower CGT bill.