The first special-needs academies will not open until at least 2011, heads have been told.
Department for Education officials fear their formation will be more complex because of the different ways special schools are currently funded and their stronger links to local authorities.
Education Secretary Michael Gove and his head of special educational needs and disability, Hardip Begol, have told teachers and campaigners the schools should be developed "slowly".
Heads and governors at 23 special schools have expressed interest in becoming academies, a move that would mean they were exempt from SEN legislation.
Martin Absolom is head of Oakley Special School in Tunbridge Wells, which is one of the 23.
"We only wanted to express an interest (in becoming an academy), and we don't want to be left out if that's the way things are going," he said. "It's certainly not going to be an easy thing to achieve - our links with the local authority are so umbilical.
"When we heard about it, we thought it was either a folly or it was dynamic. We've not been able to make up our minds yet."
Tara Flood, director of the Alliance for Inclusive Education, said she hoped the DfE would wait until the the Government's SEN review had taken place to set up the academies. "If officials have any sense, they will wait to see the findings of the review," she said.
A DfE spokeswoman said: "We are committed to giving special schools the same additional freedoms as mainstream schools, and to develop a streamlined process for conversion of outstanding special schools."