Yale University will increase its endowment spending by more than one-third in the 2008-9 fiscal year, university officials announced today. The university will raise the payout rate on its $22.5-billion endowment to a floor of 4.5 percent and a ceiling of 6 percent, up from 3.8 percent or $843-million this year. Yale’s president, Richard C. Levin, said the increased payout of $1.15-billion would be used for student aid and biomedical research.

The announcement pleased Sen. Charles E. Grassley of Iowa, who, as the Senate Finance Committee’s top Republican, has considered introducing a proposal to require wealthy universities to spend at least 5 percent of their endowments.

“This is a great day for parents and students,” Mr. Grassley said in a written statement. “The Yale bulldog might take a bite out of tuition costs for middle- and low-income families.”

But Mr. Grassley also said he hoped Congress would continue discussing an endowment-spending mandate. Several higher-education associations criticized such a proposal, calling it simplistic. —Paul Fain