The short-term funding bill the U.S. Senate passed early Saturday to keep the government running through Dec. 11 would provide about $843.9 billion for defense, nearly half of the about $1.7 trillion in annualized budget authority it covers, according to a new Congressional Budget Office estimate.

The measure would largely maintain federal agencies at prior-year funding rates, but it carves out billions in exceptions, including for Navy shipbuilding programs with prior-year cost increases.

CBO estimated the stopgap at about $1.7 trillion in annualized budget authority and $1.87 trillion in outlays across the 12 appropriations bills it extends. Of that, $843.9 billion in budget authority is for defense.

The bill sets aside about $2.61 billion across 20 programs for what it calls "prior year shipbuilding cost increases," an exception to the spending restrictions in the stopgap, according to the legislation.

The largest amounts go to the Columbia-class submarine program, at $566.5 million, and the Virginia-class submarine program, at $561.1 million, along with $379.2 million for aircraft carrier refueling overhauls and $324 million for the Carrier Replacement Program.

The bill also provides up to $2.85 billion in Procurement, Defense-Wide funds to be spent as "necessary for National Security Systems," a separate provision from the shipbuilding funds.

Continuing resolutions typically hold agencies to prior-year rates and restrict new production starts or funding increases, but lawmakers can write in exceptions for specific programs.

The CBO estimate also identifies $1.54 billion in emergency-designated budget authority for the EPA's Superfund program. CBO says the money stems from a 2023 law rather than from a new emergency designation in the stopgap.

The bill now returns to the House, which must approve the Senate's amendments before it can go to President Donald Trump.

Unless the House acts before the fiscal year ends Sept. 30, the government would shut down Oct. 1; if the measure becomes law, it would fund the government through Dec. 11.