In order to improve the governmental efficiency, effectiveness and transparency, an important part of e-government is the digitalization of documents and the processing of these documents through electronic channels. Such a critical document in business process chains is the invoice, which is why the European Commission strives to increase the adoption and diffusion of electronic invoicing (e-invoicing) among public and private sector organizations. However, the adoption rate among businesses is still low and especially very small firms resist using e-invoicing.By collecting quantitative and qualitative survey data of 416 German companies resisting the usage of e-invoicing, we confirm and explore factors affecting the resistant behavior towards the electronic exchange of invoices and elaborate on differences in those factors with organizational size. In particular among micro firms, the lack of knowledge regarding the theme and procedure of e-invoicing represents the relatively most important influencing factor, while comparatively larger firms also expect huge change management efforts.