Assessable value for captive consumption: apply prior year profit before tax percentage to current cost of production to determine value. Assessable value for captively consumed goods is to be calculated by determining current-year cost of production-including material, labour, overheads, administrative expenses, advertising, depreciation and interest-and loading onto that cost the profit margin derived from the previous year's audited profit before tax, expressed as a percentage of the prior year's cost of production; the prior methodology referencing net sales may continue, and supporting accounts and CA certificates must be scrutinised.