This was at a large company, salaried employees. We accrued sick leave and vacation leave separately. However, each time we were out sick, we had to use a full day of vacation before we could use any of our accrued sick leave. If we didn’t have any vacation accrued and were out sick, we would have to take an unpaid day before we could use our sick leave. This also meant that you couldn’t use partial days of sick leave for appointments or anything like that.
No wonder this place has massive turnover.