The leaders of the Senate Finance Committee have urged the U.S. treasury secretary to change the federal tax form that many tax-exempt entities file each year, with the goal of ramping up scrutiny of the complex financial operations of private nonprofit colleges and hospitals. The letter from Sens. Max Baucus (D-Mont.) and Charles Grassley (R-Iowa) offers some new insights -- worrisome to college tax experts -- into the senators' interest in the possibility of penalizing institutions that are perceived as spending too small a proportion of their endowment assets.