In order to cope with the COVID-19 pandemic, many schools have been closed for several months as of March 2020 in Germany. The unplanned and rapid shift to distance learning formats has led to fears that extensive learning deficits will be created and educational inequality will be further exacerbated. This paper, therefore, investigates the impact of the COVID-19 pandemic on spelling skills (capitalisation, sounds and letters, separate and compound spelling and punctuation) of students in German-speaking countries. For this purpose, we use granular learning process data from an online learning platform for spelling competences with over 1 million solved exercise sets. We compare successful completion of exercise sets before the pandemic and after the first wave of the pandemic and estimate personal competence by a Rasch model. The result shows a loss of competence in 2020 and an increase in inequality in some grade levels and spelling domains. A linear model cannot confirm an overarching loss of competence.