The two inspectorates are a year into a joint five-year inspection programme to assess the quality of support for SEND children and young people in all 152 local authority areas across England.
But analysis of the first 30 areas inspected, in the 12 months to May 2017, has revealed "significant concerns" about support in nine areas, with each asked to produce a written statement of action on how they would tackle failings.
Common areas of concern include "weak" strategies to meet requirements under the Children and Families Act 2014 to ensure all children and young people from birth to 25 years old receive an education, health and care plan, outlining the support they need and how providers will help improve their outcomes.
"The plans were primarily education plans, with very poor evidence of how health or social care needs had been considered and what the intended outcomes were," the report states.
It adds that senior management in the areas were generally found to be failing to ensure services were focused on improving outcomes for children and young people with SEND. In addition, elected council members were not effectively holding services to account or challenging lack of progress.
Six areas were specifically failing to address a rising level of exclusions and poor attendance among SEND pupils. Strategies to deal with the issues was found to be poor and there was a lack of commitment from local schools to improve attendance and reduce exclusions.
Other areas of concern include poor access to specialist and therapeutic support and a lack of engagement with parents, including poor handling of disputes and a lack of transparency in decision making.
"Consequently, families experienced a postcode lottery for the quality of support and provision they receive," the report adds.
"They indicate that some local authorities are not using joint working effectively, she said.
"This is most apparent in education, health and care plans, where in too many local authorities the child's education needs are the main focus.
"The result is that disabled children's health and care needs are not fully assessed or met."