WASHINGTON (AP) — Treasury Secretary Janet Yellen notified Congress on Friday that the U.S. is projected to reach its debt limit on Thursday and will then resort to “extraordinary measures” to avoid default.

Those measures include delaying some payments, such as contributions to federal employees’ retirement plans, in order to provide some headroom to make other payments that are deemed essential, including those for Social Security and debt instruments.

Yellen said while Treasury can’t estimate how long the extraordinary measures will allow the U.S. to continue to pay the government’s obligations, “it is unlikely that cash and extraordinary measures will be exhausted before early June.”