The 21-year-old, who starred in Brazil's successful Confederations Cup campaign in June, joined the Catalans for 57 million euros in one of the most high profile transfers of 2013 to date.
However, Radio Globo reporters unearthed details which reveal that the Brasileirao club did not get paid around €40m of the full figure as the Camp Nou club splashed out for a signing-on fee, agent fees and other bonuses.
Santos may receive more financial profit from the move eventually through arranged friendlies that the two sides agreed to, with the first on August 2 in Spain, and potential objectives for the forward to achieve which were included in the contract.
The third parties were named as the Teisa Group and DIS, which have controlling interests in Neymar, who is widely regarded to be one of the rising stars in world football.
The documents also show that Neymar’s father wanted his son to depart Brazil ahead of the World Cup because he did not want him to become a "hero or villain" at next summer's tournament in the South American country.
The attacker, who has scored an impressive 24 goals in 39 Selecao appearances, will meet up with his new Barca team mates next week.