Capital Gains Tax due on gifted house that was then gifted to spouse

I purchased a house for £140,000 in 2015. It was my main residence & had a lot of work done on it including an extension. In 2019 I gifted it to my then girl friend for £0, it became her main residence. The estimated value at the time on the HMLR form was £300,000. We married in 2020. In 2022 she gave it back to me (for £0), it was our main residence. Estimated value at the time on the HMLR form was £325,000. In 2023 we started renting the house out and lived elsewhere. If I sold the house next year, I understand that there will be some capital gains due as it has been rented out (for over 9months). My question is how will the capital gains be calculated, from which date and what amount? For capital gain calculation purposes; will the date I owned it from, be 2022; and the capital gain amount, be the difference from the estimated value at that time of £325,000 compared to the price I sell it for? [I know I have to work out how long I lived there (+9months) vs rented it for and apply as a percentage against the capital gain amount to give taxable cap gain amount]

Hi,
HMRC cannot comment on future events as legislation may change. however, based on current guidance it is from the date of purchase and you can then claim private residence relief for the period you lived in the property:
Capital Gains Tax: what you pay it on, rates and allowances
Thank you.