In the government formation process, coalition partners make decisions about the inner workings of their future government. However, whether the initial allocation of competencies has the desired effects is uncertain, and deals may therefore be subject to change when the government is in office. This study analyses the frequency of changes in portfolio design (i.e. the distribution of competencies among government ministries and office holders) for 112 coalition governments in eight West European democracies (1970–2015). Its central argument is that in uncertain and complex bargaining situations, coalition partners have greater difficulty finding mutually beneficial deals, and changes to the initial allocation of payoffs are therefore more likely. The results indicate that preference divergence and strenuous coalition negotiations make portfolio design reforms more likely, but show no consistent effect of the familiarity among government parties. These findings show how the bargaining context during government formation foreshadows coalition governance over the cabinet’s life-cycle.