School funding: 'No more' savings possible in some NI schools
"No more" can be done in some schools to save money, the head of the Education Authority (EA) has said.
Sara Long made the comments in a letter to all school principals in Northern Ireland.
She also acknowledged what she said was their "growing frustration" with a lack of adequate funding.
In July, a Westminster committee said a lack of money was having a devastating impact on schools in Northern Ireland.
Ms Long took up the post of chief executive of the EA in April 2019.
In her letter, she said principals and school leaders had been working in "challenging circumstances," due to ongoing action short of strike by teaching unions.
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More than 450 schools in Northern Ireland could not balance their books in 2019, according to EA figures.
"We acknowledge your growing frustration with the lack of adequate funding to enable you to fully deliver high-quality learning experiences for all children and young people," Ms Long wrote.
"We realise that for some schools, there is no more that can be done to affect further savings.
"We acknowledge the challenges you face in relation to meeting the diverse and increasingly complex special educational needs of our children and young people and we will provide detailed action plans to address recommendations."
The EA has previously overspent its own budget, mainly due to rising costs to support children with Special Educational Needs (SEN) in both mainstream and special schools.
A number of parents and some school principals have expressed dissatisfaction with the support some children with SEN receive.
Ms Long also said the authority and teaching unions were developing new measures to address the abuse of school staff, including on social media.
"We are acutely aware of your concerns relating to the abuse of staff in schools, which we share with you," her letter said.
"We deem any abuse completely unacceptable."
As well as ongoing industrial action by the four main teaching unions over pay and workload, a union which represents many school principals is also currently taking action short of strike.