That is according to a stunning report in El Mundo, which outlines how the Catalan giants made a significant calculation in paying the Brazilian international during his time at the club and are now seeking to address the error.
As outlined by ESPN back in June, the Blaugrana won a court case against the player following a bonus dispute and Neymar subsequently had to pay the club €6.7m.
The court dispute had centred around Neymar claimed that the Blaugrana owed him an unpaid bonus of €43m following the last contract he signed with the club in 2016.
Back in September, it was revealed by El Mundo Deportivo that the superstar owes €34.6m to the Spanish state in unpaid taxes and debt accumulation.
The Paris Saint-Germain forward is said to owe the Spanish Treasury a grand total of €34,624.26.60 as of December 31, 2019, and as published on 30 September.
Now aged 28, Neymar starred for the Catalan giants between 2013 and 2017 before joining Paris Saint-Germain in a world record transfer worth €222m.