After coming under fire last week for lavish spending, the chief executive of EduCap Inc., a nonprofit student-loan company, said critics should “take it up with Congress.” On Monday, a powerful member of the U.S. Senate’s Finance Committee referred to that challenge as he opened an inquiry into the lender’s operations, The Washington Post reported today.

EduCap, which makes private student loans under the name Loan to Learn, pays its chief executive, Catherine B. Reynolds, $1-million in annual compensation. The nonprofit organization also bought a $30-million private jet and donates millions of dollars to a foundation run by Ms. Reynolds’s husband, according to the Post. EduCap was criticized last year for inviting college financial-aid directors to an all-expenses-paid conference in the Caribbean.

In a letter sent on Monday to Ms. Reynolds, the Finance Committee’s two leaders asked for documentation on how EduCap sets loan rates, approves customers, and spends money. The senators also raised questions about whether EduCap deserved its tax-exempt status.

“The taxpayers and Congress need full confidence that public-charity executives aren’t enjoying private jet vacations on the backs of students being charged 18-percent loan interest rates,” said Sen. Charles E. Grassley of Iowa, the top Republican on the committee. —Paul Fain