New York regulators have launched an investigation into Earnin, a Silicon Valley-backed cash-advance app, over concerns that it may be skirting state lending laws, The Post has learned.

The probe follows an exclusive report by The Post last week that questioned whether the increasingly popular app’s requests for voluntary “tips” in exchange for advances on paychecks amounted to high-interest payday lending, which has been banned in 15 states including New York.

Linda Lacewell, acting superintendent of the New York Department of Financial Services, subpoenaed the company on Wednesday for 21 different categories of records, according to a source familiar with the investigation.

That includes records of the names of Earnin’s New York customers, the size and number of their transactions, and orders to convert the “tip” amounts it has requested for advances to annual percentage rates, or APRs — and to assume that the fees count as interest, the source said.

Last week, The Post reported that Earnin encouraged users to leave a tip of anywhere between zero and $14 on a $100 weekly loan. Users who don’t leave a tip appear to have their credit restricted. Meanwhile, a $14 tip would equate to a 730-percent APR — nearly 30 times higher than New York’s 25 percent cap.

The DFS is demanding all documents that Earnin has given or presented to venture capital firms as well as any research “to encourage consumers to voluntarily leave tips,” the person said.

The state is also investigating any disclosures — or lack thereof — made to New Yorkers about the Truth in Lending Act, the source said.

Experts told The Post that Earnin is operating in a legal “gray area,” since it says the money isn’t a loan and could be violating TILA by not disclosing interest rates.

The regulator also asks for corporate information, like organizational charts, company bylaws and policies, and the profits and losses for the last six years, the person said.

Earnin’s parent company, Activehours, has until April 16 to respond, the source told The Post.

A spokeswoman for Earnin didn’t immediately respond to a request for comment.

The Post first reported on March 22 how Earnin — backed by Silicon Valley investors including Andreessen Horowitz, DST Global and Spark Capital — has left some users mired in debt as it avoids state and federal lending laws that make fees more transparent.

Earnin’s CEO, Ram Palaniappan, denied the company was a payday lender, and declined to answer questions about compliance with the TILA, which would require the company to disclose APRs to customers.