Sick leave among Northern Ireland's 9,300 council staff costs ratepayers more than £15m a year, the Audit Office has found.
Only two councils had below average sick leave levels
It said in a report that local councils' 14-day a year average is the highest in the UK.
Larne Borough Council topped the table, with an average of 20 days lost - a third of them stress-related.
Magherafelt had the lowest level of absenteeism, with seven days taken per member of staff a year.
Council chairman Paul McLean said it had taken radical action.
"We have a policy in place that, irrespective of a doctor's line, people are referred to the occupational health department along with their line manager," he said.
It and Fermanagh were the only two councils that managed to stay below the UK average.
While some councils have managed to reduce absenteeism, others like Coleraine have seen the rate climb to more than three weeks a year.
Stress, depression, fatigue and mental health issues accounted for 20% of time taken off, the Audit Office found.
It said stress-related absences cost councils £3.1m last year, but only eight councils had implemented a stress or mental health policy.