To celebrate her 27th birthday, Mistress Marley, a professional dominatrix from Harlem, flew to Tulum, Mexico, where she rented a modern four-bedroom villa with a limestone pool, private beach and personal chef.

For four days, she and six friends swam in the warm Caribbean waters, went zip-lining in the Mayan jungle and dined on fresh lobsters and tequila at boho-chic restaurants.

Whenever she wanted money, she said, she would set up her iPhone on the coconut-filled beach and command her online suitors to chip in.

“Tulum has been amazing thus far. Keep funding my trip!” she posted to her Twitter followers in late January, along with her CashApp handle and a 15-second video showing off her curvaceous bikini body, bright red fingernails and flowing dark tresses.

Soon, she said, money began flowing into her account. “Please take all of my money for your trip, I don’t deserve it,” wrote Betaboy10, who gave $500, according to screen shots she provided to The New York Times. Another, named SubMike00, sent $250. A user who goes by Peter Zapp sent $400, along with the message: “I’d do anything to be owned by you.”

Welcome to the lucrative world of financial domination, a form of B.D.S.M. that has flourished during the pandemic, when many sex workers and their customers have migrated online because of social distancing precautions. The concept is simple, even if the allure is not immediately self-evident: “finsubs” (short for “financial submissives”) send monetary “tributes” to a financial dominatrix, who could be any gender, in exchange for being humiliated and degraded.

“It’s controlling someone through their wallet,” said Mistress Marley. (The Times agreed to identify her only by her professional name to prevent stalkers from finding her.) “I love waking up every day realizing that submissive men pay all my bills and I don’t spend a dime.”

Trysts take place mostly online, though there can be in-person encounters. And the humiliation could be as fleeting as a few moments, or persist for hours during so-called draining sessions, when the dominatrix hurls a barrage of insults and demands that ends only when a monetary cap is reached or a finsub’s bank account hits zero — whichever comes first.

In its purest form, financial domination is not transactional. Sending money is the kink, and finsubs offer tributes without expecting anything in return. “The arousal is in the act,” said Phillip Hammack, a professor of psychology at the University of California, Santa Cruz and the director of its Sexual and Gender Diversity Laboratory. “It’s about that loss of control.”