PurposeDespite the literature highlighting the relevance of mergers and acquisitions (M&As) as strategic options for organizations’ evolution, such events maintain a high failure rate. All stages of M&As generate considerable stress on management accounting systems (MASs) and related actors. This study aims to investigate management accounting change (MAC) throughout M&As to expand knowledge on the technical side of these changes. A deeper understanding of these changes and their relationship to the implementing agents could illuminate the causes of M&A success and failure.Design/methodology/approachThe study uses an in-depth, qualitative case study analysis of two companies that completed an M&A. The MAC process was investigated based on Sulaiman and Mitchell’s (2005) typology. The authors collected information from internal documents, interviews, external reports and public information.FindingsThe findings indicate that MAC in M&As represents a comprehensive change that goes beyond the modifications outlined in Sulaiman and Mitchell’s (2005) original framework; the post-deal integration period can be broken down into early and full sub-phases; and the success of the MAC process rests on the different roles played by various change agents.Originality/valueTo the best of the authors’ knowledge, this study is among the first to apply and deepen a MAC framework focused on technical changes to MASs in the context of M&As. To date, the literature on M&A has mainly focused on behavioral or organizational changes while neglecting the technical dimension. In addition, by considering all the stakeholders of MASs, this study’s analyses expose the role of change agents who are not generally considered in the accounting literature.