Companies could find themselves in a costly mess in the coming year with their debt as lenders move to a different overnight bank lending rate.

“This could be a big, sleeper issue,” Susan Cosper, technical director of the Financial Accounting Standards Board, said at a conference of the American Institute of CPAs in Washington.

U.S. regulators and accounting rulemakers are concerned for companies as the benchmark for establishing interest rates on loans in the U.S. switches from LIBOR, the London Inter-bank Offered Rate, to SOFR, the Secured Overnight Financing Rate.

Companies need to make themselves aware of the implications...