Radio station Cadena Ser announced on Friday that "according to legal sources, prosecutors will ask him to appear as a witness in the tax fraud case against Barcelona president Josep Maria Bartomeu, the club and former president (Sandro) Rosell".
According to the same sources, the Madrid court that deals with complex financial cases will accept the request.
Cadena Ser added that the request that Neymar appears in person before the court is justified by the fact that he personally signed nine of the 13 contracts being investigated.
The Catalan club and their former and current presidents are accused of hiding the real cost of the transfer that brought the Brazilian star, now 23, to Barcelona from Santos in 2013.
Prosecutors say Neymar cost "at least 83,371,000 euros" ($90.7m) and not the 57 million initially reported by Barcelona.
A trial could take place in the autumn and might only last a week, Cadena Ser added.
Prosecutors last month requested a prison sentence of two years and three months for Bartomeu and seven and a half years for his predecessor Rosell.
The Madrid court is also calling for a fine of 22.2 million euros ($24.1 million) against the club over the transfer deal.
Judge Pablo Ruz said various contracts produced "were designed to cover or hide the fact that in reality they represented a higher cost for Barcelona" in order to "avoid or significantly reduce the money paid to the tax authorities".
The cost of the transfer rose steeply when Barca decided to bring forward an initial agreement signed in 2011 for the player to move in 2014 by a year as other clubs, including rivals Real Madrid, attempted to hijack the deal.
Rosell resigned over the scandal in January 2014 with his then vice-president, Bartomeu, taking charge.