Ai Weiwei, the artist and government critic who emerged last week from nearly three months in police custody, is facing nearly $2 million in fines and unpaid taxes, according to his mother and a lawyer retained by his design company.

On Wednesday, Pu Zhiqiang, the lawyer retained by Mr. Ai’s design company, said he had filed a request for an administrative review before the tax authorities. By law, he said, such a hearing must take place within 15 days. At the moment, Mr. Pu said he was hamstrung by a lack of financial documents, which were seized by the police shortly after Mr. Ai was detained in early April.