Hi Florence Conville,
If you use recreated records, you will need to show which figures are estimated or provisional.
If you do not have records:
Capital Gains Tax: what you pay it on, rates and allowances
If you wish any valuation being used to be checked prior to completion of the return, HMRC provides the following service.
If you wish HMRC to check your valuation:
Market value
There are no specific instructions on how any estimated figures are reached.
You will need to ensure that they are supplied on a just and reasonable basis and evidence that they have used all available information & means to obtain any realistic valuations or estimates supplied.
Thank you.