The business offloads bookkeeping job to a firm that brings its employee to work in the local office. The business offloads bookkeeping job to a firm that carries out the job at its own premises. Cost. The average cost for a full-time in-house bookkeeper is between $30,400 and $39,800. The hourly cost can be between $20 and $50. Charges mostly depend on the complexity of the task. Some outsourcing firms charge a flat-rate.