The last three government shutdowns cost taxpayers a combined $4 billion, according to a bipartisan report from the Senate Permanent Subcommittee on Investigations.

The vast majority of the cost was associated with back-paying federal workers for time that they were barred from working.

{mosads}“The last three government shutdowns cost taxpayers nearly $4 billion — at least $3.7 billion in back pay to furloughed federal workers, and at least $338 million in other costs associated with the shutdowns, including extra administrative work, lost revenue, and late fees on interest payments,” the report found.

The report examined the 16-day shutdown in 2013, which was triggered by a fight over ObamaCare, as well as a 3-day shutdown in January 2018, which largely focused on immigration and the 35-day shutdown that lasted from late December 2018 through January 2019, which centered on President Trump’s proposed border wall.

“This report reaffirms what I’ve always said: Federal government shutdowns don’t save money, they actually cost taxpayers billions of dollars,” said Sen. Rob Portman (R-Ohio), the committee chairman.

Earlier this year, the nonpartisan Congressional Budget Office (CBO) estimated the last government shutdown, the longest in history, shaved $11 billion off the economy.

The combined total of furlough days during the three shutdowns combined was nearly 15 million — or a total of nearly 57,000 years of lost productivity for agency employees, according to the report.

Another shutdown could potentially be around the corner. Congress is expected to vote next week on legislation to avert a shutdown and fund the government into late November.

But controversy over the wall, and Democratic opposition to refilling military accounts Trump reprogrammed to build it under an emergency declaration, have thrown a wrench in the appropriations process.

“I hope this report serves as a reminder to the President and Congress about the real consequences and costs to taxpayers when we do not do our jobs,” said Sen. Tom Carper (D-Del.), the committee’s ranking member.

“Democrats and Republicans must come together, stop governing through continuing resolutions that are woefully inefficient, and do our most basic job by ensuring that our government has the funds it needs to operate,” he added.

The report comes as lawmakers have less than two weeks to get a deal to fund the government past Sept. 30. The House is expected to vote next week on legislation to avert a shutdown and fund the government into late November.

Jessica Campisi contributed to this report which was updated at 11:15 a.m.