Buy Before Sell and CGT

Hi I want to buy a property before selling my own and would like to know if I would be liable for CGT under the following scenario: The current property, I bought in 2003, is and has always been my main residence. If I buy a new property and exchange contracts on 1st September 2024. I do not physically move into the new property until 1 January 2025 and from then it will become my main residence (Would spend time renovating) I sell the old property and exchange contracts: A) anytime before 1st January or B) after 1st January 2025 Thanks

Hi Angus Mitchell,
We cannot comment on scenarios.  
Private resident relief is avaialable to only one property at a time.  
If you buy a second property, you will need to write to H.M. Revenue and Customs Self Assessment BX9 1AS Stating the address of the property you wish to be your main residence.  
Private residence relief is the fraction that is the number of months a property was your main residence plus a further 9 months over the number of months you owned the property.
This fraction is applied to the gain and the value deducted from the gain.  
There is a calculator for capital gains at Tax when you sell property.  
Please also read the guidance on private residence relief at HS283 Private Residence Relief (2024)
Thank you.