Neymar has seen assets worth almost €45 million including a yacht, a jet and several properties frozen by the authorities in Brazil.
A Sao Paulo court rejected an appeal from the Brazilian striker last week and started issuing warrants to freeze the assets, Brazilian media reported.
Last year, Neymar, his family and related businesses were found guilty of evading 63 million reals in taxes (€14 million) between 2011 and 2013 when he was playing for Brazilian club Santos. He has denied any wrongdoing.
The 23-year-old used the jet to travel to Brazil for World Cup qualifying matches and holidays.
Iagaro Jung Martins, an auditor with Brazil's tax agency, told The Associated Press that Neymar is not likely to go to jail if he pays what regulators say he owes.
"He can still appeal that decision, but it is a step forward," Mr Martins said. "Nothing changed to what was in place last year. If he pays what he owes, the case is closed. Our legislation isn't too harsh."
The assets seizure is the latest in a streak of bad news for the Brazilian star off the pitch.
On February 2 Neymar and his father were questioned for three hours in a Madrid court about the player's transfer to Barcelona.
The case was brought by Grupo Sonda, which invested in Neymar early in his career and was allegedly entitled to 40% of the total transfer amount.
Barcelona maintains the deal cost the club £51.3 million. Santos officially received a payment of £12.8 million, with the remaining £38.5 million going to a company owned by Neymar's father, Neymar Santos.
But investigations in Spain later showed that Barcelona spent nearly £62.3 million to acquire Neymar.
Former and current Barcelona presidents and representatives of Santos were also questioned. The Brazilian club also claims to have been hurt by the transfers. All parties denied any wrongdoing.