Main Residence Relief for Part owned property

I have purchased a third share of my parents property and up until 5 months ago, this was my main residence for the last 30+ years. I have now moved away and rent a house. My brother now wants to live in the area of the property I occupied and will be buying the third share. I purchased the share for £200k Ten years ago and will sell it for £300k (gain of £100k). My question is, now that I am renting and treat this new rental as my main residence, how long do I have to claim main residence relief on the gain from the sale of the third share? Is it too late already to claim or is there a limit, or does transferring the share to a family member (brother) have any kind of exemption from capital gain?

Hi BackMeUp,
You would qualify for Private Residence Relief for the period you lived in the property plus the final 9 months.
As you have already left the property, you have 4 months left to finalise any sale without any Capital Gains Tax implications.
Thank you.