In this work we present the FAIRsFAIR service assessment framework, a framework for assessing how well research data infrastructure services support FAIR data. The framework focuses on providing guidelines on how services can be made to optimally improve the FAIRness of the data that they are used for. This work was inspired by a combination of literature describing the expectations users have from FAIR data services, and refined by the authors based on feedback from the community gained e.g. through workshops. This framework is the last deliverable of the T2.4 task group in the FAIRsFAIR project, and it will be presented to the European Open Science Cloud (EOSC) where we expect the most direct usage of the framework.