Does documentary proof reqd for Cost of Improvement in case of Capital Gains ?

Bill or receipt or acknowledgement is required to substantiate the claim for improvement

Obtain a Detailed Estimate/Valuation Report from any Income Tax Approved Valuer whereby the detail of construction and improvement/s will be certified by the expert. This will serve the purpose in want of relevant vouchers/receipts etc.

Dear Sir

Can any one help me in providing the info for the below:

whether we can show that we have paid bills in cash to the contractor.Pls help?