Dutch employers should prepare for a sharp rise in workers calling in sick from September, occupational health provider Arbo Unie has said.
The organisation described September as the start of the annual absence season.
Arbo Unie studied sick leave reports recorded between 2020 and 2025.
Its analysis found that the number of reports in September was 69 percent higher than in August on average.
Occupational physician Corné Roelen said the increase does not mean employees are unwilling to return to work after their holidays.
Many companies become busier in September. Employees also come into contact with more people as they return to their normal routines.
The colder weather also marks the beginning of a period when colds and flu become more common.
Nearly three-quarters of the sick leave cases recorded in September 2025 lasted less than one week.
A typical absence lasted about four days.
However, Arbo Unie said some cases developed into long-term absences. Mental health problems, including stress, remained the leading cause of prolonged sick leave.
Sick leave levels usually reach their highest point during January, February and March. Colds and flu contribute to the winter increase.
Separate figures from ArboNed and HumanCapitalCare showed that the national sick leave rate fell slightly from 4.8 percent in June 2026 to 4.7 percent in July.
The July rate remained higher than the 4.4 percent recorded during the same month in 2025.
