Business-financial decision making represent prime activity of top management. Growing complexity in the business ,market and rapid technological change require fast and appropriate answer of top management. Confident and efficient system of internal calculation gives confident base, for making financial decision and strategic as well. Companies of industrial sector in Serbia can significantly improve their business performance by improving internal calculation systems. The preservation and strengthening market position of a company can only be achieved by continuous cost control, based on reliable accounting, and adequate system of internal calculation.