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HMRC internal manual

Capital Gains Manual

Valuation: post transaction valuation checks: costs of negotiation

The costs reasonably incurred by a customer in making any valuation or apportionment submitted for a post transaction valuation check are allowable deductions but any costs incurred in actually making the submission or in furthering subsequent negotiations are not deductible in computing the gain or loss on the relevant disposal.

A fuller explanation of whether valuation costs are or are not allowable as deductions in computing a gain is given at CG15260.