CGT When changing primary residence

If I change my primary residence, is any CGT when I sell the original residence calculated on the total increase since the original purchase some years ago or from the recent date that I switched residences?

Hi Peter Evans,
You need to confirm to HMRC in writing, where you have more than one property, which is your main residence.
Tax when you sell your home
If you do not, you run the risk of HMRC deciding your main residence based on the fact of the case.
Private residence relief is only available on one property at a time, which is why you need to nominate.
Please  have a look at the guidance on private residence relief here:
HS283 Private Residence Relief (2023)
For more information
Thank you.