PHOENIX — Dozens of charities that use Arizona's income tax credit program for donations for private school scholarships are being asked to spell out how they use the program, which is coming under its first real scrutiny since it was launched more than a decade ago.

The chairman of a House committee formed to examine the program and recommend possible improvements said Wednesday that he's sending a letter to scholarship tuition organizations, asking for dollar figures and details on their application and approval processes.

"We don't want to be guessing and making policy on a guess," said Rep. Rick Murphy, R-Glendale. "Once we have that information then we'll be at a point where we can discuss some ideas."

Murphy's letter asks the scholarship organizations for their "prompt cooperation" but adds that the committee can subpoena the groups to attend a hearing and produce documents.

The House committee is one of two legislative panels formed after two Arizona newspapers, the Arizona Republic and the East Valley Tribune, published investigative stories on the program approved in 1997. It provides individual donors with dollar-for-dollar income tax credits.

The newspapers reported there is minimal state oversight of the program and no requirement for scholarship groups to consider recipients' financial status. The newspapers also found that some scholarship groups permit donors to earmark donations for specific students.

House Speaker Kirk Adams, a Mesa Republican who supports school-choice initiatives, established Murphy's committee after House Democrats organized an unofficial, bipartisan task force. Both panels are supposed to make recommendations for possible legislative action in the 2010 regular session.

School-choice advocates have said they regard the Democratic-formed tax force as hostile to the program and that they intend to cooperate only with the official committee.

The official committee's first meeting on Wednesday included testimony from numerous program supporters.

Tiffani Motley of Gilbert said it has helped her afford to send her 15-year-old son to a Christian high school where the small-school environment "has blossomed him."

"Without this program, I would have to work three jobs," Mottley said.

In contrast, the task force's first meeting included testimony from a Northern Arizona University accounting professor who heads a Flagstaff scholarship group on changes he proposes for increased accountability and transparency of the program.

In other testimony Wednesday, a Revenue Department official said scholarship groups are required to report numbers and amounts of both donations and scholarships but that she has no authority to audit them.

Senior economist Georganna Meyer said she sometimes asks the groups questions when their figures don't indicate compliance with the law's requirement that no more than 10 percent of donations be used for administrative costs.

"But I have no authority over that and they're well aware of that," Meyer said.