Maintenance of cost records ensures per unit cost calculation and reconciliation with audited financial statements for compliance. Companies subject to these rules must keep cost records and books containing prescribed particulars and maintain them regularly to calculate per unit cost, cost of operations, cost of sales and margins for each product or activity. Records must follow accepted cost accounting principles and standards, be maintained to enable cost and operational control, be reconciled with audited financial statements with variations explained, and be retained for the specified statutory retention period.