But the 54-year-old told the Guardian he did not owe the money and would challenge the demand, adding: "It's a game they play all the time … They needed an excuse to take me away for 81 days."
Ai's family and supporters always believed his detention was in retaliation for his social and political activism. During his interrogations, Ai was questioned about issues such as subversion of state power rather than his accounts.
Ai said the authorities told him the tax was owed by Fake, the company that handled his affairs but was legally registered by his wife.
"I am a designer for the company; I am not the legal representative, nor the manager," he said. "I never signed papers or made a deal or transferred money – I was nothing to do with the accounting. They said I was the 'actual controlling person' of the company."