Kalamazoo College President Eileen Wilson-Oyelaran is among college leaders sending letters this month about the looming fiscal cliff to top congressional leaders and President Barack Obama. Wilson-Oyelaran’s signature is one of six signed at the bottom of a letter urging lawmakers and the president to keep charitable deduction tax rates at 35 percent as leaders in Washington develop a plan before automatic tax hikes and spending cuts take place in January. The letter was also sent to U.S. Rep. Dave Camp, R-Midland, the chairman of the House Committee on Ways and Means. The tax deduction on charitable giving worries colleges because education gets the majority of its contributions from the wealthy, who benefit most from deductions. The higher the marginal tax rate, the bigger the tax break the donor receives. The charitable deduction, which dates to 1917, would cost the government about $250 billion over the next five years, and proposals for reform vary.