Stamp Duty Explained: How SDLT Works When You Buy a Home

You find the house, you scrape together the deposit, you get the mortgage agreed, and then a number you had not fully planned for lands on the completion statement: stamp duty. For a lot of buyers it is the single biggest cost of moving after the deposit itself, and it is the one most people understand the least. It arrives as a line on a solicitor's bill rather than something you actively pay, which is exactly why it catches people out.

Stamp duty, properly called Stamp Duty Land Tax (SDLT), is a tax you pay to HMRC when you buy a property or land in England and Northern Ireland over a certain price. Scotland and Wales run their own versions under different names and different bands. This guide explains how the tax is worked out, who pays more and who pays less, when it is actually due, and the points where getting it wrong costs real money. The aim is that by the end you can sense-check your own bill rather than just trusting the total at the bottom of the page.

What is stamp duty and how is it calculated?

Stamp Duty Land Tax is a tax charged on the purchase price of a property. The key thing to understand is that it is tiered, not a single flat percentage. You do not pay one rate on the whole price. Instead the price is split into bands, and each slice of the price is taxed at the rate for that band, in the same way income tax works across tax bands.

That tiered structure matters because it changes how you should think about the bill. A common mistake is to assume that nudging just over a threshold taxes your entire purchase at the higher rate. It does not. Only the portion of the price that sits inside a higher band is taxed at that higher rate, so crossing a threshold by a small amount only ever costs you the higher rate on that small amount, not on everything below it.

The rates and thresholds are set by the government and change from time to time, often at a Budget, so the bands that applied to a friend's purchase two years ago may not be the bands that apply to yours. Because the figures move, the safest approach is to check the current bands against your specific price rather than rely on a remembered number. A conveyancer calculates this precisely as part of the legal work, and an experienced conveyancing team will confirm the exact figure before you commit. For an authoritative, always-current breakdown of the bands you can also check the government's SDLT guidance.

First-time buyer stamp duty relief

First-time buyers get a meaningful break on stamp duty, and it is one of the few areas where the rules genuinely favour the person buying. If you are a first-time buyer purchasing a home to live in, you pay nothing up to a set threshold and a reduced rate on the slice above it, up to an upper price limit. Above that upper limit, the relief disappears entirely and you pay the standard rates like any other buyer.

The detail that trips people up is the definition of a first-time buyer. To qualify, you must never have owned a residential property anywhere in the world, including inheriting a share of one or owning one jointly. If you are buying with another person, both of you have to be first-time buyers for the relief to apply. One partner having owned a flat years ago is enough to lose the relief on the whole purchase, which surprises a lot of couples.

Because the saving can run into thousands, it is worth being certain you qualify before you bank on it. The relief is claimed through the SDLT return your conveyancer files, so there is no separate application, but the claim has to be correct. If first-time buyer status is part of how you have worked out your affordability, it is sensible to confirm it early rather than discover at completion that the bill is higher than planned. This is also a natural point to make sure your mortgage and overall costs still add up once the real stamp duty figure is in front of you.

Stamp duty on second homes and buy-to-let

If the property you are buying means you will own more than one residential property, you usually pay a surcharge on top of the standard rates. This higher rate applies across every band, not just the top one, which makes second homes and buy-to-let purchases noticeably more expensive than a comparable main residence.

The surcharge is decided by a simple test: at the end of the day you complete, will you own an additional residential property? If yes, the higher rates apply. This catches more people than just landlords and holiday-home buyers. If you are buying your next main home before you have sold your current one, you can find yourself temporarily owning two properties and paying the surcharge, even though you only intend to keep one.

There is some relief built in for that situation. If you sell your previous main residence within a set window of buying the new one, you can usually reclaim the surcharge you paid. The reclaim is a process with its own deadlines, so it pays to know it exists and to flag it to your conveyancer at the outset rather than after completion. For landlords building a portfolio, the surcharge is simply a structural cost of each purchase, and it feeds directly into whether a buy-to-let stacks up. Getting the figure right before you offer, rather than after, is the difference between a deal that works and one that quietly does not. A conversation that joins up the buy-to-let mortgage and the conveyancing means the surcharge is in the numbers from the start.

When do you pay stamp duty, and how?

Stamp duty is due within 14 days of completion. That is a tight window, and missing it brings penalties and interest, which is why in practice you almost never handle it yourself. Your conveyancer files the SDLT return and pays HMRC on your behalf out of the funds you transfer to them ahead of completion. The money has to be with your solicitor before you get the keys.

This is the part that reframes how stamp duty should sit in your planning. Because it is paid in cash at completion and is not rolled into your mortgage, it has to come from your own savings alongside your deposit and your legal fees. Buyers who budget carefully for the deposit and then forget the stamp duty can find themselves short at the last moment, which is a stressful place to be days before moving.

Some buyers manage the cash-flow squeeze by borrowing slightly more against the property to free up savings to cover the tax, but whether that is wise depends on your affordability and your wider borrowing, not just the immediate cash need. It is exactly the kind of trade-off worth talking through before you commit rather than deciding under pressure. The cleanest approach is to treat stamp duty as a known, plannable cost from the moment you start house-hunting, work out the figure for your likely price range, and hold it back in cash so it is never a surprise.

The mistakes that cost buyers money

Most stamp duty problems come from a handful of avoidable errors. The first is assuming the headline rate applies to the whole price and over-estimating the bill, which can make a buyer rule out a property they could actually afford. The tiered system is gentler than it looks, and understanding it can open up options.

The second is the opposite: forgetting the surcharge on an additional property and under-budgeting. A buyer who assumes standard rates on a second home can be several thousand pounds short. The third is missing a relief you were entitled to, whether that is first-time buyer relief or the reclaim on a replaced main residence, and simply overpaying because nobody flagged it.

The thread running through all of these is that stamp duty sits at the join between the legal side of a purchase and the financial side, and it is easy for it to fall down the gap between the two. The buyers who get it right are the ones who know their figure early, factor it into both their mortgage affordability and their cash at completion, and have someone confirm the exact amount and any reliefs before contracts are exchanged. It is a known cost with knowable rules, and it should never be the thing that derails a move at the last minute.

(Tax treatment depends on individual circumstances and may change in future.)

Stamp duty is one of the largest costs of buying a home and one of the most misunderstood, but the rules behind it are knowable. It is tiered, so crossing a threshold is rarely as punishing as it sounds. First-time buyers get a genuine break, second properties carry a surcharge that catches more people than just landlords, and the whole bill is due in cash within 14 days of completion. The buyers who never get stung are simply the ones who work out their figure early and join up the legal and financial sides of the purchase. If you would like the exact stamp duty position on a specific property confirmed before you commit, that is precisely the kind of thing it pays to check with people who handle both the conveyancing and the mortgage in one place.