Since the U.S. government stopped paying for most services due to the fight between President Donald Trump and Congress over funding for promised barriers on the border with Mexico, the economy has suffered $3.6 billion in lost production as of Friday, according to estimates by the economists at S&P Global Economics.

“It will only take another two weeks to cost the U.S. economy more than the $5.7 billion that the White House requested" to fund Trump’s current proposal for additional border barriers, S&P said in its statement. That’s “a modest impact on the $19 trillion” U.S. economy, but it will add up, and continue to “shave approximately $1.2 billion off real GDP in the quarter for each week that part of the government is closed.”

The shutdown will be the longest in the history of bickering between presidents and Congress as of Saturday, S&P added. “The longer this shutdown drags on, the more collateral damage the economy will suffer.”

S&P counted both “direct” cost, such as losses to employees and contractors who aren’t being paid and business delays by companies that rely on government services, and “indirect economic costs," such as canceled personal spending by unpaid workers and contractors who were counting on public jobs.

Over time, employers that rely on federal business or government services would be forced “to reduce staff, extending the pain.”

The shutdown stops a few of the wheels of capitalism. For example, S&P notes that the Securities and Exchange Commission has had to stop work on applications by companies for initial public stock offerings (IPOs). The leading ride-sharing companies, Uber and Lyft, are among large U.S. employers that have applied to go public in the near future.

While federal employees should get missed wages retroactively, “the many government contract workers who are out of work because of the shutdown are unlikely to get back pay,” S&P added, with those “living paycheck-to-paycheck” the most vulnerable to falling behind on housing and loan payments.

Taxes are still due April 15, but the IRS has sent workers, who collect taxes, home until they start getting paid again, reducing federal revenues.

Will Americans get tax refunds on time?

“The Trump administration has taken steps to send out IRS refunds in spite of the government shutdown, which will alleviate some of the squeeze on households across the U.S. that may have other plans for that big refund,” S&P notes.

Even if Trump’s efforts to get refunds flowing are successful -- which S&P says isn’t yet clear -- and despite last year’s Trump tax cuts that boosted real income for millions of companies and families, tax practitioners note that a minority of Americans, including middle-income parents with kids in college and those paying high state and local taxes, won’t be getting refunds as big as in past years, and some could end up owing instead of collecting checks.

A longer shutdown could also tarnish Trump’s cherished record of economic growth. The 16-day government shutdown in October 2013 “reduced fourth-quarter GDP by 0.3 percent,” S&P added, citing Bureau of Economic Analysis research. “Productivity lost from furloughed government workers will never be regained."