Under the current system – which applies to England & Northern Ireland – you'll only pay the rate for the proportion of the property that's at that rate. It's quite complex, so here's an example to better illustrate how it works:

Let's assume you're buying a property for £500,000.

You pay nothing below £125,000.
You pay 2% on between £125,001 and £250,000, which is £2,500.
You pay 5% on the value of the property between £250,001 and £500,000, which is £12,500.

So in total this means you'll pay £15,000 (£0 + £2,500 + £12,500).

As the price you pay for a new property increases, so do the rates of stamp duty. You pay a percentage of the cost, and the rate payable leaps up at a set of thresholds – but, you only pay the proportion of the purchase price that's actually above the thresholds at the higher rate.

People buying an additional property (ie, in addition to any they already own) will be penalised in the form of an extra stamp duty charge on any property costing more than £40,000.

Under stamp duty rules that took effect in 2014 you pay different rates for different proportions of the property price. This will mean that the following additional property stamp duty rates will apply on each portion of the purchase price on buy-to-let and second homes.

It's not actually called stamp duty in Scotland anymore. A reform brought in by the Scottish Government in April 2015 means it's now referred to as 'land and buildings transaction tax'.

However, while the name's changed, the principle hasn't. It's still a lump-sum tax that anyone buying a property or land costing more than a set amount has to paya. And it's a remarkably similar system to the one the rest of the UK uses, the main difference is the thresholds it uses are at different rates.

Here's an example of how the new Scottish system works, for an example-property priced at £300,000.

You pay nothing below £145,000.
You pay 2% on between £145,001 and £250,000, which is £2,100.
You pay 5% on between £250,001 and £300,000, which is £2,500.

So in total this means you'll pay £4,600 (£0 + £2,100 + £2,500).

The Welsh Revenue Authority (WRA) is responsible for collecting and managing Land Transaction Tax (LTT), which replaced Stamp Duty Land Tax in Wales last year.

LTT works similarly to the old stamp duty system, but the Welsh Government has set the thresholds for the tax bands at different rates.

Here's an example of how the new Welsh system works, for a single residential property priced at £300,000 and filed at main rates.

You pay nothing below £180,000.
You pay 3.5% on between £180,001 and £250,000, which is £2,450.
You pay 5% on between £250,001 and £300,000, which is £2,500.

So in total this means you'll pay £4,950 (£0 + £2,450 + £2,500).

WRA have a simple guide to higher rates. They also have an LTT calculator.