The city is reducing payments to scores of contractors providing tutoring to students in underperforming public schools, according to an August 12 letter from the city’s Department of Education that was obtained by The New York Sun.

According to the document, federally mandated tutoring programs that use public school facilities will face a 9% cut in their rate of payment in the coming academic year.

The reduction “could have a material impact on educational quality, program design, and ultimately, student results,” the executive director of the Education Industry Association, Steven Pines, said.

Under the Supplemental Educational Services provision in the federal No Child Left Behind Act of 2001, students attending schools that have failed to make “adequate” progress on standardized tests for two consecutive years are eligible for free extra help, through a program that is funded entirely by the federal government but administered by local school districts.

Beginning last academic year, the city allowed parents whose children are eligible for what is known as SES to choose from a menu of private tutoring services. They receive up to $2,200 a student in federal funds, though most providers charge substantially less than that. More than 87,000 city students enrolled in tutoring under the act last year, and the city received about $79 million from the federal government for SES, according to a department spokeswoman, Kelly Devers.

According to Mr. Pines, whose trade association says it represents more than a dozen tutoring services in New York City and about 700 member organizations nationwide, the typical SES provider offers about three hours of tutoring a week. Some providers offer one-on-one help, while others hold classes for up to 12 students. The city’s recent 9% cut might force cash-strapped tutoring services to increase their student-to-teacher ratios, Mr. Pines said.

Under non-binding guidelines issued June 13 by the federal Department of Education, schools should make their facilities available to SES providers “on the same basis and terms as are available to other groups that seek access to the school building.”

The city education department does not generally charge rent for its space, although principals can impose a usage fee to cover additional security and maintenance costs if they must keep buildings open after hours or on weekends, to accommodate groups that meet inside public schools, according to Ms. Devers.

The new 9% cut does not replace any usage fees that principals may have imposed on SES providers, according to the city agency’s general counsel, Michael Best.

Not all tutoring services choose to use space in public schools. For example, Kumon North America, which estimates it will provide extra help in math and reading to about 100 students in grades one through eight in Brooklyn and Manhattan next year, will conduct all tutoring sessions in its own learning centers, according to Kumon’s vice president of education and school support, Matthew Lupsha.

Mr. Best said the 9% cut is an attempt to “level the playing field” between tutoring services that use public school space and others, such as Kumon, that do not.

“We want to make sure that the federal money we’re entrusted with is actually spent on services,” Mr. Best said. If a provider chooses to use public school space for free, Mr. Best said, “we’re not going to reimburse you for rents that you’re not paying.”

Mr. Pines, the trade association executive director, said that although schools have a right to charge a reasonable fee for the use of their space, it is “patently unfair” for the city to impose the fee unilaterally after it has already signed a contract with SES providers.

Mr. Best said, though, that the 9% cut is negotiable. He also said the 9% figure is a “reasonable rate” that the department set after studying other contractors’ budgets to estimate average rent costs.

By comparison, Chicago imposes a $75-per-pupil fee on SES providers that use public school space. That amounts to less than 4% of the maximum per-pupil payment that service providers in the Windy City may receive from the federal government, according to Mr. Pines.

In its June 13 guidelines, the federal education department noted that many parents want to enroll their children in tutoring programs that are held inside public school buildings, “because this eliminates the need to transfer their children to another site after school has ended.” A small fraction of the 134 SES contractors authorized for the city schools operate online only.

City education officials said in January that only about one-fourth of students who are eligible for SES programs had actually enrolled in the free courses. The New York Sun reported in January that some SES contractors have offered rewards, including $100 gift certificates and MP3 players, as an incentive for students to attend the extra help sessions.

The city’s SES contractors range from local not-for-profit groups to large corporations such as Kaplan and Princeton Review.