Can I use my 140 working days per year by working more than 20 hours a week at the university?

As a student in Germany with a residence permit, your right to work is generally limited to 140 working days a year (Arbeitstagekonto; a day of up to 4 hours counts as half a day). If you work more than 20 hours per week during the semester, these hours might be counted as full days, which would reduce your overall quota quickly. Additionally, certain jobs, like student assistant positions (HiWi), might have different regulations. It's always best to confirm your specific situation with the local foreigners' office (Ausländerbehörde) to avoid any issues.