Standard cost estimates are created once a year or per month for planned and production orders. Production costs are received when finished stocks are received, and month-end closing processes include posting material costs, debiting secondary costs, and crediting production output. Variances are also calculated during month-end closing processes. Product costing in SAP includes costing variants to determine bills of materials, routings, and default dates for costing. It also includes costing sheets to determine updated material prices and valuation controls for materials, activities, and overheads.