Historic property values

[MrsBossyPants]

I need to organise filing for CGT for a property just sold in the UK. The owner (my eldrerly relative) is a non UK resident/tax payer and only needs to pay CGT on the increase in value from April 2015 to now. The owner has mislaid the valuation done in 2015.

Is there a reliable source of historic values that will be accepted by HMRC?

I put the postcode into the UK sold house prices option on Rightmove and worked it out from the sold house prices in the local area for similar properties. The valuation was accepted with no issues, although luckily it was a fairly standard house and nothing unique or hard to put a price on.

You can pay a valuer to value it as at 2015.

Or you can look on Rightmove etc and guesstimate, which is very commonly done but just keep in mind that HMRC can ask to see records etc and challenge.