Calculating and Using Dual Charging Rates The expected costs for the Maintenance Department of Stazler, Inc., for the coming year include: Fixed costs (salaries, tools): $64,900 per year Variable costs (supplies): $1.35 per maintenance hour The Assembly and Packaging departments expect to use maintenance hours relatively evenly throughout the year. The Fabricating Department typically uses more maintenance hours in the month of November. Estimated usage in hours for the year and for the peak month is as follows: Assembly Department Fabricating Department Packaging Department Total maintenance hours Actual usage for the year by: Assembly Department Yearly Monthly Hours Peak Hours 4,500 390 6,700 1,300 10,800 910 22,000 2,600 3,960