The short answer
Can you add stamp duty to your mortgage? In most cases, yes. Most lenders will let you increase your loan amount to cover the stamp duty bill rather than requiring it in cash on completion day, alongside your deposit and legal fees. It's treated as extra borrowing — added to your mortgage balance and repaid, with interest, over the full term.
Work out your stamp duty first
Before deciding whether to add it to your mortgage, see exactly how much you're dealing with.
Open the stamp duty calculator →How it actually works
Adding stamp duty to your mortgage simply means borrowing more. If you're buying a £300,000 property with SDLT of £2,500 and you want to fund it through your mortgage rather than cash, your lender increases your loan amount by £2,500 to cover it. It doesn't require a separate application or product — it's a bigger loan against the same property.
The catch is that this also increases your loan-to-value (LTV) ratio. If you were borrowing exactly 85% of the purchase price before adding stamp duty, folding the tax bill into the loan might tip you into the next LTV band up — say 90% — and lenders price mortgage rates in bands. A higher LTV can mean a noticeably worse rate on the entire loan, not just the stamp duty portion, so it's worth checking this before assuming it's a free option.
Why it usually costs more than paying upfront
Anything added to your mortgage accrues interest for as long as you hold that borrowing — typically 20 to 25 years, unless you overpay it off early. Paying the same amount in cash at completion costs you exactly that amount and nothing more.
Worked example: £10,000 stamp duty at 4.5% over 25 years
That £10,000 stamp duty bill ends up costing an extra £6,675 in interest if it's rolled into the mortgage rather than paid upfront — nearly two-thirds more than the original amount, purely from spreading it over the term. See our overpayments guide if you do add it to the loan and want to clear that portion faster.
When it makes sense anyway
Rolling in the stamp duty isn't always the wrong call. It can make sense when:
- You genuinely don't have the cash — your deposit and legal fees already use up your available funds, and the alternative is delaying or losing the purchase
- You're confident you'll overpay it down quickly — most lenders allow penalty-free overpayments up to a limit each year, so you can add the stamp duty now and clear it faster than the full term implies
- The LTV impact is negligible — if adding it doesn't push you into a worse rate band, the main cost is just the extra interest on a relatively small amount, which may be worth the cash-flow flexibility
It's a trade-off between cash-flow now and cost over time — there's no universally right answer, only what fits your situation. If you're also weighing your deposit size against this decision, see our mortgage deposit guide for how LTV affects your rate more broadly, as set out in HMRC's Stamp Duty Land Tax guidance on what's owed and when.
Frequently asked questions
Can I add stamp duty to my mortgage?
In most cases, yes — many lenders will let you borrow the stamp duty as part of your mortgage rather than paying it separately in cash at completion. It simply increases your loan amount (and therefore your loan-to-value), so it's subject to the same affordability and LTV checks as the rest of your borrowing.
Does adding stamp duty to my mortgage affect my interest rate?
It can, indirectly. Rolling stamp duty into your loan increases your loan-to-value ratio, and mortgage rates are priced in LTV bands — if the extra borrowing tips you into a higher LTV band, you could be offered a worse rate on the entire loan, not just the stamp duty portion.
Is it better to pay stamp duty upfront or add it to my mortgage?
Paying upfront in cash is almost always cheaper over time, since anything added to the mortgage accrues interest for the full term — often 25 years or more. Adding it to your mortgage makes sense mainly when you genuinely don't have the cash available at completion and the alternative is delaying or losing the purchase.
Can first-time buyers add stamp duty to their mortgage?
Yes, the same principle applies to first-time buyers as to home movers — though first-time buyer relief often means there's little or no stamp duty to add in the first place below the relevant threshold. Where relief doesn't fully cover the price, any remaining stamp duty can usually be added to the loan on the same basis.
This guide is for general information and doesn't constitute financial advice. Whether your lender allows stamp duty to be added to your mortgage, and on what terms, varies by lender and by your individual circumstances — always confirm with your mortgage adviser or lender directly.