Ontario's Ministry of Education has released new guidelines clarifying when a school can ask students for extra cash.
Under the guidelines, released Friday, schools cannot charge for textbooks, science lab materials, art supplies or musical instruments.
Schools cannot apply a fee to anything that is mandatory, essential for classroom learning, or the completion of a course, including a student registration fee.
"There should be absolutely no fee associated with any requirement for course completion for graduation," Education Minister Leona Dombrowsky said.
Schools can, however, continue to charge for yearbooks, extracurricular activities and upgraded materials not essential to a course.
The province's Education Act already prohibited fees for any curriculum requirements students need to graduate high school, but the new guidelines put the ban in clearer language.
The clarification comes after advocacy group People for Education released a report Thursday saying fees charged for courses, student activities and athletics are on the rise across the province.
Fifty-three per cent of Ontario high schools charge fees for art classes, 41 per cent charge fees for physical education and 26 per cent impose extra costs for music courses, said spokeswoman Annie Kidder.
Many schools rely on fees for a substantial portion of their operating expenses, said Kidder, adding that some schools raise only $1,000 from student fees while others raise as much as $90,000 a year.
Schools with a higher proportion of low income students have lower average course fees, which suggests fees are charged on a "what the market will bear" basis, said Kidder.
Callers to CBC's Ontario Today said Friday that they have had to pay for course materials and lockers for their children.
Fees build inequity into the system and are a barrier for many students, said Zane Schwartz of the Ontario Student Trustees' Association.
"We should not be in a position where, when it comes to course selection, that you don't want to pick art or you don't want to take gym for another year because your family doesn't really have that $20 or $50 or $100," said Schwartz.
The new guidelines make clear what fees are appropriate and require boards to track all the fees charged and the amount they bring in, Dombrowsky said.
NDP Education critic Rosario Marchese said the fees that remain are a loophole that will lead to a two-tiered education system favouring richer schools that can afford the extras.