The Ombudsman examined 3,067 complaints last year, down nearly 16% on 2015.
Peter Tyndall said the fall in complaints was largely due to the drop in cases against the Department of Social Protection, which he said would be expected for a country coming out of recession.
24% of cases were upheld, 4% were partially upheld while assistance was provided in another 19% of complaints. Just over half, 54%, were not upheld.
Mr Tyndall said his office made several interventions in the Reasonable Accommodations at Certified Examinations scheme, which helps ensure that students with disabilities are not disadvantaged in State exams.
He said the scheme is now simpler, and help is now automatically given for Leaving Cert students if they were covered for the Junior Cert.
In one case which was resolved, a woman got a bill for nearly €20,000 which the Department of Social Protection said had been overpaid to her.
On investigation, the woman's income had been incorrectly calculated and it turned out she was due a refund of €700.
Since April this year, the office can now take complaints from people living in Direct Provision centres, and staff members have visited centres.
So far, around 14 formal complaints have been received although some issues have been resolved informally.
Complaints have related to the weekly allowance, exceptional needs payments, staff, food and transfer costs.
The Ombudsman hopes to be allowed to examine complaints from prisoners later this year.