Beginning Sept. 1, 2009, the fee to transfer points from American Express Membership Rewards to U.S.-based airline frequent flyer programs will increase. Currently, the cost to transfer points to U.S. carriers is $0.0005 with a cap at $75 per transaction; with this change, the new charge will be $0.0006 with a $99 cap.

For example, if you transfer 100,000 points, the fee will be $60–a 20 percent increase from $50. In the fine print about the change American Express said, “We charge this fee to offset the federal excise tax we must pay on such conversions. The fee may be more or less than the actual amount of the excise tax we pay on any individual conversion.”

But as disgruntled cardholders have mentioned, not every program that allows points to miles conversions passes along this fee–and American Express has chosen to up their transfer fee even though the federal excise tax has not increased.