A new policy from the Trump administration could leave thousands of immigrants scrambling to keep their jobs while they await renewals of their work permits.

Previously, many immigrants were able to extend their work permits automatically upon submission of a renewal application. Now, U.S. Citizenship and Immigration Services is doing away with that policy, and forcing people to wait until a renewal request is approved before any extension.

That change, which went into effect on Thursday, is significant because it can take the federal government months to process renewals due to a massive backlog of applications. That means immigrants could lose their jobs if their work permit expires before their renewal process is completed by USCIS.

As WGBH reports, immigrants are able to begin applying for renewal six months before the expiration of their work permit, though approvals can often take longer than that.

Ultimately, experts believe this policy could lead to immigrants being let go by their companies because they don’t have a work authorization. Additionally, it could enable companies to exploit immigrants by continuing to use their labor off the books.