The English Schools Foundation will administer proficiency tests to all applicants under a new policy that may boost the chances of children of non-English- speaking families.
Parents will also be interviewed, and children who attend ESF-affiliated kindergartens will lose their priority in admission to primary schools.
But critics note that the moves might be unfair to English-speaking children from middle-class families who cannot attend local government and subsidized schools because of language difficulties.
In the current system, children of parents who state that the main language spoken at home is English are given higher priority for interviews.
Those who speak Cantonese are given lower priority, though the ESF said it is difficult to verify the language information.
The new admission policy will be effective this August for students to be admitted in the 2014-15 school year.
ESF chief executive Heather Du Quesnay said there will not be any difference between Asian students and other expatriates, and the system will not deprive English-speaking children of opportunities.
She denied the new policy is connected with the subvention scheme.
"It's extremely difficult to verify what parents tell us on the forms [on the language of their children]," Du Quesnay said.
"Some parents are quite uncomfortable about whether the category we allocated is appropriate."
All applicants will have to sit an English proficiency test while parents will also be interviewed and make a statement to verify their commitment to an ESF- style education. Priorities will remain for children of ESF staff, siblings of existing students, those with nomination rights and children of alumni.
But children who attend ESF Educational Services-operated kindergartens will no longer have priority. However, those attending ESF kindergartens this school year and those who have gained a place for this September will not be affected.
Education lawmaker Ip Kin-yuen is worried the new policy will deter non-local students from coming to Hong Kong.
Leticia Lee See-yin, chairwoman of the Federation of Parents' Association of Hong Kong, said even if local students have a bigger chance of enrolling, they still have to compete with English- speaking students in the same pool.