Less than half of states are meeting their obligations to appropriately serve students with disabilities under the nation’s special education law, federal education officials say.

In an annual review, the U.S. Department of Education found that only 22 states deserved the “meets requirements” designation for the 2015-2016 school year. All other states were placed into the “needs assistance” category.

The findings issued this summer come from a mandatory assessment of state compliance with the Individuals with Disabilities Education Act. The ratings are based on how well states meet their obligations to serve students with disabilities ages 3 to 21.

Federal officials look at student performance and functional outcomes for kids with disabilities as well as how well states follow through with procedural duties like completing special education evaluations.

If a state fails to achieve the “meets requirements” level for two or more consecutive years, IDEA stipulates that the Education Department take enforcement action, which can include redirecting or withholding funds, developing a corrective action plan or mandating other changes.

This year’s determinations reflect a drop in the number of states found to meet requirements. Last year, 24 states received that designation.

States receiving letters indicating that they met their obligations under IDEA include Alabama, Delaware, Iowa, Kansas, Kentucky, Massachusetts, Minnesota, Missouri, Montana, Nebraska, New Hampshire, New Jersey, North Carolina, North Dakota, Oklahoma, Pennsylvania, South Dakota, Tennessee, Virginia, West Virginia, Wisconsin and Wyoming.

The remaining states were labeled “needs assistance.”

No state received the more extreme designations of “needs intervention” or “needs substantial intervention.”