DHS staff took more sick days than any other public service agency in 2017-18.

New data shows that while Department of Human Services staff were the sickest, the National Archives of Australia had the highest overall rate of unscheduled absences.

The Australian Public Service Commission says the rate of unscheduled absences, including sick leave, carers leave and miscellaneous leave, has flattened after a peak in 2014-15.

The Department of Agriculture and Water Resources saw one of the most significant drops in the rate of unscheduled absences taken by its staff - from 14.9 days in 2015-16, to 14.5 in 2016-17 and 14 last year.

It comes after the department's staff voted for an agreement that required them to provide a medical certificate if they missed work for three or more days in a row.

Most agencies offer 18 days of annual paid sick leave – higher than the 10 days required by the national employment standards.

Agencies vary in their requirements for how many consecutive days an employee can take off work without providing a medical certificate or other evidence.

More details are available here.