An image forming apparatus includes a printer, an input device configured to receive a user input, and a processor configured to acquire identification information that specifies a task in a predetermined service and is input through the input device, acquire document type information about document types used in the predetermined service based on the acquired identification information, generate a code for the task by encoding the acquired identification information, and control the printer to print an image of one of the document types and the generated code on a sheet of paper.