Answer by taking a quote from the following article:

Ai Weiwei (Chinese: Ai Wei Wei ; pinyin: Ai Weiwei,  English pronunciation ; born 28 August 1957 in Beijing) is a Chinese contemporary artist and activist. His father's (Ai Qing) original surname was written Jiang (Jiang ). Ai collaborated with Swiss architects Herzog & de Meuron as the artistic consultant on the Beijing National Stadium for the 2008 Olympics.

In June 2011, the Beijing Local Taxation Bureau demanded a total of over 12 million yuan (US$1.85 million) from Beijing Fa Ke Cultural Development Ltd. in unpaid taxes and fines, and accorded three days to appeal the demand in writing. According to Ai's wife, Beijing Fa Ke Cultural Development Ltd. has hired two Beijing lawyers as defense attorneys. Ai's family state that Ai is "neither the chief executive nor the legal representative of the design company, which is registered in his wife's name."  Offers of donations poured in from Ai's fans across the world when the fine was announced. Eventually an online loan campaign was initiated on 4 November 2011, and close to 9 million RMB was collected within ten days, from 30,000 contributions. Notes were folded into paper planes and thrown over the studio walls, and donations were made in symbolic amounts such as 8964 (4 June 1989, Tiananmen Massacre) or 512 (12 May 2008, Sichuan earthquake). To thank creditors and acknowledge the contributions as loans, Ai designed and issued loan receipts to all who participated in the campaign. Funds raised from the campaign were used as collateral, required by law for an appeal on the tax case. Lawyers acting for Ai submitted an appeal against the fine in January 2012; the Chinese government subsequently agreed to conduct a review.  In June 2012, the court heard the tax appeal case. Ai's wife, Lu Qing, the legal representative of the design company, attended the hearing. Lu was accompanied by several lawyers and an accountant, but the witnesses they had requested to testify, including Ai, were prevented from attending a court hearing. Ai asserts that the entire matter - including the 81 days he spent in jail in 2011 - is intended to suppress his provocations. Ai said he had no illusions as to how the case would turn out, as he believes the court will protect the government's own interests. On 20 June, hundreds of Ai's supporters gathered outside the Chaoyang District Court in Beijing despite a small army of police officers, some of whom videotaped the crowd and led several people away. On 20 July, Ai's tax appeal was rejected in court. The same day Ai's studio released "The Fake Case" which tracks the status and history of this case including a timeline and the release of official documents. On 27 September, the court upheld the 2.4 million tax evasion fine. Ai had previously deposited 1.33 million in a government-controlled account in order to appeal. Ai said he will not pay the remainder because he does not recognize the charge.  In October 2012, authorities revoked the license of Beijing Fa Ke Cultural Development Ltd. for failing to re-register, an annual requirement by the administration. The company was not able to complete this procedure as its materials and stamps were confiscated by the government.

What happened in the tax case?
the Beijing Local Taxation Bureau demanded a total of over 12 million yuan (US$1.85 million) from Beijing Fa Ke Cultural Development Ltd.