Jackson Hewitt Tax Service plunged 12 percent amid reports it lacks financing for about half its refund-loan program this tax season.

The firm is seeking a new source of cash for “refund- anticipation loans” after regulators last month ordered Santa Barbara Bank & Trust out of the business, according to a federal filing yesterday.

Jackson Hewitt said it’s not sure new funding can be obtained, and that if it doesn’t succeed, “it would have a material adverse effect on the company’s business, financial condition and results of operations.”

Refund-anticipation loans are used to attract clients who need cash immediately by offering a short-term loan, typically lasting a few weeks, that’s based on the expected amount of their tax refund. “We still continue to explore options,” Jackson Hewitt spokeswoman Sheila Cort said. “We’re in discussions with some large banks and some other funding sources.”

Jackson Hewitt sank 52 cents to $3.92 in New York Stock Exchange composite trading; archrival H&R Block added 1.4 percent to $22.27.