Two months after promoting plans to send out “limitless” numbers of missionaries, the International Mission Board (IMB) of the Southern Baptist Convention (SBC) faces a financial crisis.

IMB president David Platt announced Thursday that the agency needs to cut at least 600 missionaries and staff in order to balance its budget. Those cuts are needed to make up for a $21 million deficit for 2015.

The first of the cuts will come from voluntary retirements, followed by a restructuring. Overall, the IMB could release as many as 800 employees, according to an FAQ posted on the IMB’s website.

Currently, the IMB has about 450 staff and about 4,700 missionaries overseas, down from 5,600 in 2009. Platt said earlier this year the total number of missionaries would likely drop to about 4,200—a 25 percent decline from 2009.

Platt also announced plans Thursday to change how the IMB does business.

The agency currently has two major sources of ongoing funding: donations to the annual Lottie Moon Christmas Offering, and funds from the SBC’s Cooperative Program. That income has been supplemented in recent years with reserve funds, as well as proceeds from the sales of missionary housing and other property overseas.

Overall, the agency spent about $210 million more than it brought in over the past 6 years, IMB leaders said.

Platt, who became the IMB's president a year ago, told reporters that he didn’t want to question the decisions made by past IMB leaders. The property sales have helped IMB missionaries spread the gospel, he said.

But the agency was running out of properties to sell. And relying on sales, along with drawing down reserves, was not a sustainable strategy.

“We cannot continue to overspend,” he said in a statement. “For the sake of short-term financial responsibility and long-term organizational stability, we must act.”

The IMB had $168 million in reserves as of June 2015, according to its report to the SBC’s annual meeting. The agency’s total budget for 2015 was about $301 million. That report also shows about a $3 million deficit for 2014 and 2015.

Scott Moreau, editor of Evangelical Missions Quarterly, said the IMB staff cuts could be a sign of things to come. Since the 1700s, he said, evangelicals have used the “William Carey” model of missions funding.

In that model, churches and individual Christians donate to a mission society, which then sends out missionaries.

It’s a model that could falter in the future, Moreau said. “This might be a step toward the demise of the centrally funded mission agency.”

Mission agencies are also struggling to replace missionaries who retire, he said.

That’s been the case for the IMB. Earlier this week, the agency appointed 42 new missionaries, and plans to continue to send new missionaries out—including an estimated 300 this year. But it won’t be replacing every missionary who retires.

Sebastian Traeger, the IMB’s executive vice president, said that agency leaders considered other options to make up the budget deficit, including reducing the number of new missionaries or selling more property.

“But none of them bring about a balanced budget fast enough, or they are not feasible to implement in the short term,” he said in a statement. “Our goal is to align our cost structure with the amount of money given to us each year.”

Earlier this summer, Platt told CT that the IMB had to change its strategy for sending out missionaries.

In the past, the IMB has focused on sending fully funded missionaries.

Now it is looking for ways to partner with missionaries sent out by local churches, or with other Baptists who are living overseas.

He said that the agency can’t raise enough money to send out all the people who want to serve in missions.

“Right now we’ve decreased [the number of sent missionaries], but it’s not because we don’t have people that want to go with us,” he said. “We’re turning people away.”

He hopes to allow retirees, students, and professionals who work overseas to be part of the IMB’s missionary programs.

“We’ve got to figure out,” he told CT, “how do we integrate [them] into intentional disciple-making and church-multiplying strategies among unreached people?”

Additional reporting by Timothy C. Morgan.