In an increasingly digital world, the accessibility of digital services is an important question of inclusion. Despite judicial requirements for accessibility of digital public services, the inclusion of accessibility into design practices is a new research area.   This research project explores how to facilitate the inclusion of accessibility into design practices by creating a methodology that centres around an accessibility maturity assessment. The result of the assessment forms the basis for the selection of design methods that are mapped to the attributes of the model.   Preliminary research consists of an interview study, desk research and unorganized research activities. A case study is conducted at the Swedish Tax Agency, the result of which form the basis of the design intervention. Case study data is analysed with the help of an accessibility maturity model, which also serves as the core of the design intervention. For the intervention, adapted, proven design methods are connected to the attributes of the accessibility maturity model. A proof of concept is created in the form of a handbook and validated with designers and employees at the Tax Agency. The validation shows that there is promise in the proposed methodology, as the use of the design practices ensure that accessibility is a part of the entire design process. Further research should investigate the use of the handbook in a case study in order to consolidate the practicalities of the methodology, as well as validate the utility of the methodology in a practical application.   Keywords: digital accessibility, digital public service, maturity model, accessibility maturity assessment, UX practices, universal design, disability   Contact: linneamichel@gmail.com