If you are looking to buy a property that will cost £500,000 and want to know how much stamp duty you will be paying on the purchase price then at the current time (2017) the amount due will be as follows:
For the purchase of a first or main residential property (for full details see this page) you will pay:
£15,000
This figure assumes there are no extenuating circumstances that would mean you are actually liable to pay the extra 3% stamp duty that is due on 2nd purchases.
If you are due to pay the extra 3%, which is due on second or subsequent property purchases (see this page for more info) then the amount that you will need to pay is:
£30,000
For property purchases at a price level of £500,000 the difference between the stamp duty paid on a first and second purchase just happens to work out at twice the cost but this is not generally the case. You can see exactly how much you would be due to pay on any other purchase price by checking out our stamp duty calculators. There is one for first property purchases and one for purchases where the extra 3% stamp duty is due.
As always, you should get professional advice on the amount and rate of stamp duty that is due on your purchase. Usually your solicitor will give you the figure that is due for you once they have all of the relevant information.