During a six-week sweep, the department inspected more than 300 businesses and said it issued more than 500 violations.
The violators placed misleading ads for so-called refund anticipation loans - also marketed as instant or 24-hour refunds.
The loans are legal - but carry huge interest rates and fees. Unscrupulous businesses often prey on people who need the money most, the department said, adding that violations are up 75 percent over last year.
"These loans are a bad idea. They often go for as much as 300 percent interest," said department Commissioner Jonathan Mintz.
"If you are a tax preparer offering refund anticipation loans, anticipate this: Consumer Affairs will aggressively enforce laws requiring you to disclose the truth about these disastrous loans."
The department also issued some advice for consumers:
The crackdown will continue through the tax season.
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