Purpose - The purpose of this thesis was to examine whether large unlisted corporate groups in Sweden plan to adopt K3 (Swedish GAAP) or plan to voluntarily adopt IFRS for their first financial year starting after December 31^st, 2013 and what factors affect the choice managers make.

Design/method/approach - In order to fulfill the purpose, 241 large unlisted corporate groups were sampled and a questionnaire was sent out to the sampled corporate groups willing to participate. A total of 109 responses were recieved.

Findings – It was found that the vast majority of large unlisted corporate groups in Sweden will adopt K3 (Swedish GAAP) for their first financial year starting after December 31^st, 2013. The reasons why these large unlisted corporate groups plan to adopt K3 is mainly because it is simpler and less costly than IFRS, or because managers are not well informed about the accounting regulations and have taken advice from their auditor. The corporate groups planning to adopt IFRS often do so because of legitimacy reasons, or because it is beneficial to adopt IFRS already for the first financial year starting after December 31^st, 2013 if there are plans to list the corporate group on a stock exchange.

Research limitations/implications – The response rate achieved was 45.2 percent, which means that the results are representative of the entire population with 95 percent confidence and a 9.2 percent margin of error. The research was delimited to Swedish large unlisted corporate groups.

Practical implications – The results give a deeper knowledge about what factors affect the choice of accounting framework for large unlisted corporate groups in Sweden and can potentially help companies facing a similar choice later on.

Originality/value – There has been very little research performed in the area of voluntary adoption of IFRS for unlisted companies. This study aimed to contribute to the closing of this gap, and to create opportunities for further research.