Freedom of Information requests made by the charity found that 45 of the 122 councils that provided figures (36.9 per cent) plan to cut education support for deaf children's support by an average of 10 per cent. Together the cuts will see spending on support for deaf children cut by £4m this year.
NDCS has warned that the latest cuts follow the loss of one in 10 specialist teachers of deaf children during the past four years.
"The government urgently needs to step in and tackle this mounting funding crisis in deaf children's education," Susan Daniels, chief executive of NDCS, said.
"By not acting, this government is putting the education of too many deaf children at risk and letting their futures hang in the balance.
"Despite councils having a legal duty to support deaf children, we are seeing the vital support that they rely on for their education torn apart.
"Deaf children are falling even further behind at school, and the government's response is nothing short of woeful complacency."
NDCS said funding needs to keep pace with the rising number of children with special educational needs. The charity also said the government should invest in training more teachers of deaf children and review its ring-fencing of school funding so councils are more able to respond to rising need.
Richard Watts, chair of the Local Government Association's children and young people board, echoed the NDCS's call for extra central government funding.
"We have made it clear for some time now that there must be additional and ongoing funding from the government to enable us to support high-needs children and their families, otherwise councils may not be able to meet their statutory duties and these children could miss out on a mainstream education," he said.
"This is why we are calling for an urgent review of funding to meet the unprecedented rise in demand for support from children with special educational needs and disabilities."
Children's minister Nadhim Zahawai said: "We want every child to have the support they need to unlock their potential, no matter what challenges they face. The high needs budget for pupils with special educational needs is £6bn this year - the highest on record and core school funding will rise to a record £43.5bn by 2020 - a 50 per cent real-terms per pupil increase from 2000.
"On top of this, last week we announced new contracts worth more than £25m to help children with special educational needs and disabilities - including those who are deaf or have a hearing impairment - have access to excellent support to help guide them through the new system of SEN reforms."
In 2017, 46 per cent of deaf children achieved grade 4 or C in GCSE English and maths compared with 70 per cent of children with no identified special educational needs.
The NDCS's findings coincided with another deaf children's charity calling for more to be done to make people aware of how support can help deaf children achieve.
Auditory Verbal UK made the call after a YouGov survey found that 58 per cent of UK adults believe children born deaf cannot learn to speak as well as hearing children.
"Deafness is not a learning disability," said Anita Grover, chief executive of Auditory Verbal UK. "We need much greater understanding of what deaf children can achieve when they have access to support in the early years of their lives.
"With technological advances in the form of cochlear implants and digital hearing aids, and access to family-centred early intervention programmes, more and more deaf children are able to speak as well as hearing children."