The amount of funding for special educational needs (SEN) in Northern Ireland is £65m - or about 14% - less than what is needed this year.
That is according to the Department of Education's impact report on its 2023-24 budget.
The department said that overall it was facing "unprecedented funding challenges and cuts".
It said it needed more than £2.9bn to run the education system in 2023-24 but had received under £2.6bn.
The education budget was cut by about £70m compared to 2022-23, but given the rate of inflation the real terms reduction is much larger.
The department also said that without any additional funding it was likely to overspend its budget.
Overall, Stormont departments are on course for an overspend of £450m this year, according to the senior official in the Department of Finance.
However, that figure is based on the assumption that there are no pay rises across public services, including in education.
Teachers in Northern Ireland have not had a pay increase for nearly three years.
