Neymar, 23, is being investigated on suspicion of evading 63 million reais ($16 million) worth of taxes between 2011 and 2013, when he transferred from the Santos football club to Barcelona, according to the Santos prosecutor's office for Brazilian tax authorities.
A federal judge in Sao Paulo froze three times the amount allegedly owed as a security measure to prevent Neymar -- whose full name is Neymar da Silva Santos Jr. -- from selling the assets before the case has been resolved and to cover eventual fines and interest payments.
The judge said the superstar "failed to report income coming from abroad" and "failed to report payments" from Barcelona. The athlete declared $19.6 million reais, according to officials.
The assets under question belong to Neymar, his father and businesses allegedly owned by the two.
The Brazilian court estimated the value of Neymar's assets was at 224.2 million reais ($57 million) at the end of 2013.
Neymar's parents told the Brazilian newspaper Folha de S. Paulo that Neymar had not evaded taxes and was not a partner in the businesses named in the court decision.
The money involved in Neymar's transfer from Santos to Barcelona is a focal point of the investigation.
Last year, Barcelona released figures that showed that the club paid 86.2 million euros for Neymar, rather than the 57.1 million euros originally reported. The team had to pay 13.5 million euros ($18.5 million) in additional taxes but denied any fiscal "irregularities."
Neymar's former club Santos was unhappy with how the transfer fee was divided up. A large chunk was paid to a company controlled by the player's father, Neymar Sr.
In most transfers the biggest payments go to the old club. Agents and other intermediaries also get a cut. Players sometimes get bonuses from their new and old clubs, depending on stipulations in their contracts.
Neymar, one of the best players in the world and a star on his national team, reportedly makes about 275,000 euros per week. Forbes magazine estimated his 2015 earnings from salary and endorsement deals at $31 million per year.