How to show value of property for CGT when no valuation done at time of 'gifting'

A family property in France was 'gifted' to me by my parents over 20 years ago. I would now like to 'gift' the property to my children and understand I would need evidence of its value when it became mine (as well as its recent value) to show if it has gained in value. But no valuation was ever done. How can I provide evidence of its value from over 20 years ago?

Hi ,
 

You will need to contact estate agents that sold similar properties in that area that were of the same standard for them to give you a valuation. You will need at least 3 in order to take an average . Thank you.