More than 1,500 National Guard members in Iowa and Minnesota have been shortchanged on their GI Bill educational benefits, and members of Congress want to know why.

To receive the maximum benefit, soldiers must have been issued orders for 730 days or more of active duty, and have served 20 consecutive months. Those who qualify receive up to $894 per month toward their educational expenses after making a $1,200 down payment.

The Iowa and Minnesota troops had all served 20 months or longer—the Iowa soldiers, in fact, were members of the “Ironman Battalion,” the longest-serving combat unit in Iraq—but the affected soldiers had originally been issued orders for less than 730 days. In some cases, they had been given orders for 725 to 729 days, according to The Des Moines Register.

In a news conference this afternoon, Rep. Bruce Braley, a Democrat of Iowa, said the House Oversight and Government Reform Committee would investigate why National Guard members had been denied benefits and whether other troops had been affected as well. He said the undersecretary of defense for personnel and readiness, David S.C. Chu, had assured him that the problem would be fixed in time for the spring semester. The promised benefits are a key recruitment tool.

Meanwhile, Congress is considering legislation, S 2139, that would eliminate the 730-day requirement, basing eligibility solely on length of service. —Kelly Field