Managing processes in contemporary organizations have shov.rn to be interrelated with long-term business relations. The purpose of the paper is to understand interrelated changes of management accounting and perceptions of different customers. The article is based on a qualitative case-study based on 32 interviews, observations and documentary studies. In the case-study, higher management of the focused organization tries to influence the perception of the largest customer, an old, internal organization, by using new, external customers as 'role-models' and by increasing reliance on management accounting. The study shows that management accounting in the company finds different roles in communication with and about the different customers, in co-development with the employees' perception of their customers. Customers act as both catalysts and frustrators to intended management accounting change and when customers are perceived as heterogeneous, an organization may end up with heterogeneous use of management accounting.