Assuming you own the property personally and its not your main residence (and benefiting from Principle Private Residence Relief), there are 2 rates of capital gains tax 18% for lower rate tax payers and 28% for higher rate tax payers.
You also have a CGT allowance which for 2018-19 is £11,700.
As a rough guide to assessing the tax
- Work out how much you have earned – Salary, Pension, Dividends etc
- Calculate your taxable gain + Sale Price – Sale Costs – Purchase Price – Purchase Costs – Improvements
- You can then deduct the CGT allowance of £11,700 from the Gain (assuming you haven’t used against other gains)
- If the total of 1 to 3 comes to more than £46,350 you pay 28% tax on the capital gain, if the total is less than £46,350 you will pay 18% on the gain until you hit £46,350 then pay 28% once you exceed it
You can now pay CGT straight away using the HMRC online service but most people do via self assessment and pay by 31st January following the end of the tax year.