Changes to Capital Gains Tax on Property Sales will only affect you if you sell or gift a residential property other than your main residence on or after 6 April 2020.
 
For such disposals it will be necessary to file a separate capital gains tax (CGT) return within 30 days of completion of the disposal and it will also be necessary to pay any capital gains tax within the same period.  The capital gain will also need to be reported on the normal tax return filed after the end of the tax year and the tax already paid will be treated as paid on account of the final liability.