Heads and principals are furious about having to open up specially for the new exams. They are already unhappy about the proliferation of entrance tests, as admissions tutors struggle to choose between students with strings of A-level A grades.
They will have to bring in staff over the holiday, and warn that some students will be disadvantaged if their school or college cannot open, forcing them to travel to another institution and sit the test in unfamiliar surroundings.
The affected exams are the BioMedical Admissions Test, a requirement for medical courses at five universities including Oxford and Cambridge, and several Oxford admissions tests. Schools have to administer these themselves.
All are scheduled to take place on Wednesday, October 31, which is in the one-week half-term for a minority of English schools and colleges, and in the second week of a two-week break for others.
John Dunford, general secretary of the Association of School and College Leaders, has written to Oxford university and Cambridge Assessment, which runs the medical test, to complain.
His deputy, Martin Ward, said: "If these tests take place in half-term, someone reasonably senior is going to have to turn out voluntarily to supervise them.
"That does not seem entirely reasonable to us, especially as we do not like the tests very much in the first place. It amounts to the university system taking schools and colleges for granted."
All Northern Irish schools will be on half-term on the test date. Maureen Stewart, deputy head of Ballyclare high, west of Belfast, said: "October 31 is the worst possible date."
A spokeswoman for Cambridge Assessment said it had consulted 200 schools which administered the BMATs last year and found that only 12 would be on half-term on October 31 this year.
"We only have a small window of time in which we can offer the tests," she said.
One possible solution to the problem of university admissions is an alternative to A-levels called the Pre-U. But this has been dealt a blow, with private schools appearing to fall out of love with it.
Eton and Harrow, which were tipped to adopt the qualification, now say they have no plans to teach it from September 2008.