Applications are no longer being accepted from authorities where 30 per cent of secondary age pupils are already at specialist schools.
Eight authorities have already reached this limit and have been told by the Department for Education and Employment that future applications will not be considered unless there are exceptional circumstances.
Thirteen more areas which are nearing the limit have been warned that preference will be given to applications from elsewhere.
Officials from the DFEE's standards and effectiveness unit have written to all 21 authorities as well as to schools which expressed an interest in applying for specialist status.
The letter said: "In order to ensure national coverage, location is one criterion used to decide which applications will be successful.
"In order to avoid schools carrying out abortive work when there is little chance of their application being successful, ministers have decided not to consider any further applications from areas where 30 per cent or mre of secondary age pupils are already in specialist schools."
In order to achieve specialist status, schools must raise pound;50,000 in sponsorship, prepare four-year development plans setting targets to improve the specialist subjects, and make provision to involve other schools and the community. In return, successful applicants receive pound;100,000 capital grant and pound;123 extra per pupil per year, initially for four years.
Current applications will not be affected by the decision. Exceptions will be made for schools which have already raised pound;50,000 and completed most of the application paperwork, but a DFEE spokesman said preference would still be given to schools from other areas.
Applications from education action zones and Excellence in Cities in these areas will still be considered, the spokesman said.
Bath and North-east Somerset, Northamptonshire, North Somerset, Northumberland, Rutland, West Berkshire, Wigan and Milton Keynes have been told that their applications will no longer be considered.
Blackpool, Cornwall, Darlington, Durham, Dorset, Leicestershire, Oxfordshire, Norfolk, Warrington, West Sussex, Wiltshire and Wolverhampton have been told they are nearing the limit.