what is activity based costing ? Solution Activity based costing is a method of costing under which overheads are allocated to departments on the basis of predetermined cost drivers . For example setup cost allocated on the basis of number of setups , manufacturing cost allocated on the basis of machine hours , rent allocated on the basis of floor area used by the department . Under this method a rate is calculated using the cost driver and same is allocated to the respective department on the basis of avialbility of the cost driver that is used to calculate the rate . Under this method total overhead is divided by the total cost driver in the company and the rate that we get is multiplied with the cost driver allocated to respective department to find the share of overhead of that respective department .