Investors in Halliburton Co., the largest American Army contractor in Iraq, got two reversals in a day on whether the company will be paid in full for feeding and housing American troops.

A spokeswoman for the Army Material Command, Linda Theis, said yesterday that Halliburton would get a waiver of government rules and full payment for now, reversing a decision announced four hours earlier that 15% would be withheld. Monday, Halliburton said it had assurances that a previous waiver, which expired Sunday, would be renewed.

The Pentagon has said the Houston company, run for five years by Vice President Dick Cheney, hasn’t provided paperwork to justify some of its Iraq costs. The dispute has contributed to a 14% drop in Halliburton shares this month.

Halliburton, the biggest oilfield services company, also is being investigated for possible violations of American anti-bribery laws related to payments by a joint venture in Nigeria and for overcharges for fuel deliveries in Iraq.

Government rules call for withholding 15% of a contractor’s payments until the company and government auditors can agree on a final price for services. Fifteen percent of Halliburton’s future invoices would equal about $60 million a month, spokeswoman Wendy Hall said. The company said it would, in turn, withhold 15% of its payments to subcontractors.

Halliburton is “waiting for clarity” from the Army, Ms. Hall said after the announcement that the government had decided not to withhold payments. She declined to comment further.

Analysts said Halliburton’s liquidity will be unaffected regardless of the Army’s decision.