Residential Property Relief

Hi We have recently sold a house that myself, my wife and my mother in law jointly bought a property in 1983.She gifted her share to my wife in 1989 and continued to live in it until she died in 1996 after which it was rented until 2023. Is my tax liability based upon the value of the house in 1996 or when it was purchased in 1983? thank you.

Hi
It is based on the purchase price in 1983.