WASHINGTON — The federal government may be in danger of becoming unable to respond to damages from future spills like the BP Gulf oil disaster unless Congress extends a per-barrel tax on oil, according to a report issued Monday by the Government Accountability Office.

The 8-cents-per-barrel tax, which funds the federal government’s Oil Liability Trust Fund, is set to expire in 2017.

The $1 billion trust fund is used to pay state and local governments for initial cleanup costs until it can be recovered from responsible parties.

Without extending the tax, which pays 92 percent of the fund, recovery money would be depleted, the GAO said.

“This could raise the risk that the fund would not be adequately equipped to deal with future spills, particularly one of this magnitude,” the GAO said.

The GAO also called for a new way of calculating the trust fund balance.

The fund is capped at $1 billion. If the cap is exceeded, the federal government would have to halt any payments to governments making claims for cleanup costs or damages.

Congress should mandate that the fund be calculated to include money that is reimbursed by responsible parties such as BP, the GAO said. Currently, all the money that is spent is assessed to the fund.

BP reimbursed $315 million to the fund as of May 31, 2011, the GAO said, money that should be subtracted from the fund spending and cap.

BP has established a $20 billion trust fund to pay for damages from the leak. Ken Feinberg, who is heading the Gulf Coast Claims Facility processing the claims, is set to appear before Congress on Thursday to provide an update of the process.

As of Monday, BP has paid $5.4 billion to people and businesses making claims for damage from last year’s leak.

The BP Deepwater Horizon exploded on April 20, 2010, killing 11 men and resulted in the worst oil discharge in the nation’s history.

About 4.9 million barrels of oil leaked into the Gulf of Mexico during a three-month period.