eForms have become a means to decrease workload and processing speed in the public sector. As eForms go beyond simply “digitally replacing” analogue systems, their potential is not yet exhausted. However, to systematically improve eForms, appropriate tools to tailor eForms to user needs and evaluate their usability are required. The objective of this paper is to develop and evaluate a user experience questionnaire for eForms. We introduce the eForms User Experience Scale (EFUXS), which is based on the psychological needs aspect of Self-Determination Theory and its three facets (competence, autonomy, and relatedness). To assess the validity of EFUXS, its results were compared with well-known usability (System Usability Scale; Brooke, 1996) and acceptance (simple acceptance scale, van der Laan, 1997) measures. In an online study with a randomized within-subject design, university students (N = 60) evaluated their experience with two versions of the same registration form. These forms were designed to implement the best practices from a governmental guide on eForms or their inverse (“worst practices”). All three scales were able to differentiate between “good” and “bad” tax-form versions. The item-analysis of the EFUXS showed acceptable to excellent internal consistency, item difficulty, and discrimination. The scale correlated with the two comparison measures, indicating convergent validity, while offering additional insights into psychological need fulfilment. This study suggests the viability of the EFUXS as a user experience measure and highlights advantages in its use to improve eForms.