An image forming apparatus that executes a job and determines a billing amount for the job depending on a parameter value given to a parameter that relates to the execution of the job, the image forming apparatus comprising: a storage that stores therein a first table and a second table, the first table defining billing amounts for a plurality of non-overlapping value ranges in one-to-one correspondence, the second table defining billing amounts for a plurality of specific values in one-to-one correspondence; and a determiner operable to refer to the second table before referring to the first table and judge whether the parameter value is identical to any one of the plurality of specific values in the second table (step S402), and if identical (Yes in step S402), determine the billing amount for the job according to the second table (step S403).