Nearly 10 per cent of children with special educational needs faced delays in getting plans as they prepared to move into high school.
Wigan Council was named among 103 local authorities that failed to deliver all the plans by the statutory deadline of February 15.
Figures obtained under the Freedom Of Information Act by lawyers Simpson Millar show 124 children in the borough needed an education health care plan or statement of special educational needs for transitioning from primary to secondary school in September.
But 12 plans - 9.67 per cent - were not completed in time.
The data shows that nationally 2,405 children were waiting for their plans, with 62 councils failing to issue them to 10 or more children.
Education solicitor Samantha Hale, from Simpson Millar ,said: “Parents of children with special educational needs are understandably often anxious about school changes, and their opportunity to review and challenge the provision set out in these plans is severely hampered if they are not provided on time.
“This is a statutory deadline, put in place to ensure a sensible and managed transition for children who otherwise might find the whole thing very stressful. If the plans are not issued on time, parents who wish to appeal the provision set out in it might not be able to have it heard by the tribunal.”
James Winterbottom, the council’s director for children’s services, said: “We gave priority to those children who were changing settings from primary to secondary, and those who went slightly over the timescale were either remaining within their current school setting or there were individual circumstances that we needed to work through with families and understand before we could issue our plan. Throughout the process we provide families and carers with close support by attending review meetings and advising on the EHC process.
“The slight delay will not impact any transitions for pupils nor their education going forward.”