The short-term housing rental service Airbnb has paid back taxes that ran into the millions of dollars to the city of San Francisco. The popular San Francisco-based company said in a statement that it has paid in full a back-tax bill. A spokesman wouldn't say how much the company paid. City Treasurer Jose Cisneros ruled in 2012 that Airbnb owed back taxes. He has declined to reveal how much money he collected so far from Airbnb, saying local law mandates confidentiality on all tax matters. Officials had estimated that Airbnb owed the city as much as $25 million, the San Francisco Chronicle reported. The back-tax issue had threatened to unravel legislation that the supervisors passed last year legalizing short-term home rentals in the city. The law mandated that Airbnb pay the city's hotel tax going forward, but it didn't address issue of back taxes. The law, which took effect Feb. 1, allows only permanent residents to offer short-term rentals; it requires hosts register with the city and get a business license and permit; and it mandates the collection of hotel tax. It also limits entire-home rentals to 90 days per year, requires each listing to carry $500,000 in liability insurance, and establishes guidelines for enforcement by the Planning Department.