HM Treasury said in its Autumn Statement and Spending Review that the change was to bring CGT into alignment for other taxpayers, such as those paying income tax through the Pay As You Earn (PAYE) system.
Currently, CGT is paid between 10 and 22 months after a disposal is made.
The government added that the current system can cause problems where a taxpayer forgets to pay, or where they no longer have enough proceeds from the sale to cover the tax charge.
The new timescale will be introduced from April 2019 to ensure that HMRC’s digital systems are able to provide support.
Chancellor George Osborne announced to Parliament today that HMRC will be made more effective and efficient for taxpayers to deal with by digitalising the service. He explained that all individuals and businesses will be able to view their tax affairs in real time, with digital tax accounts for all small businesses and individuals to be made available by 2016-17.
Further changes to CGT include the removal of a double charge sometimes required by non-residents with retrospective effect from 6 April.
HMRC will also be given powers to prescribe circumstances when a CGT return is not required by non-residents. This will add CGT to the list of taxes that the government may collect on a provisional basis.