Confusion surrounds claims that Real Madrid forward Cristiano Ronaldo criminally evaded tax estimated to be in the region of €150 million.
These are allegations that the Spanish government is investigating after news outlet El Mundo suggested Ronaldo could become embroiled in a scandal.
Jose Maria Mollinedo is secretary general of Gestha, which is the biggest workers' union among the employees of the Spanish equivalent to the UK's HM Revenue and Customs, and he says Ronaldo could be facing half a dozen years behind bars.
"We would be advising aggravated tax fraud," Mollinedo told RAC1. "This means a minimum prison sentence of two years for each defrauded year.
"If the investigation is looking at the last three years, that would mean at least six years of imprisonment.
"The congress will have to see if the tax authorities have already acted. We have seen that some Madrid players reached an agreement with them.
"We believe it is very serious that it is not being considered that there is a criminal element; that it is not being considered that there is a will to deceive.
"Considering the scale of the information [on Ronaldo], we believe that his case must pass directly to the prosecutors. We would not like that there is favourable treatment [for Madrid players]."
Ronaldo is favourite to win the upcoming Ballon d'Or having had an outstanding 2016. He won the Champions League with his club and Euro 2016 with an unfancied Portugal team.
He could feature for Real Madrid in Wednesday's Champions League clash with Borussia Dortmund, with victory promising the group's top spot.
Real Madrid have excelled on the pitch this season and lead rivals Barcelona by six points in La Liga.
Off the pitch, Barca have been beleaguered with tax fraud allegations the past 12 months. Javier Mascherano was convicted after a plea agreement and, in June, Messi was convicted for tax evasion during his time in Spain.
Most recently, Neymar and his family are being threatened by the country's prosecutors with business corruption charges over the player's transfer to Barcelona.
Ronaldo's agency have been keen to stress the player's innocence since the allegations emerged at the start of December.