Sky Sports News HQ reported the news on Tuesday:
According to the Telegraph, the prosecutor's office released a statement alleging Ronaldo deliberately hid his image rights earnings through the creation of a "business structure" in 2010.
The prosecutors filed the suit after receiving a report from Spanish tax agency AEAT.
Per Adriana Garcia of ESPN FC, Ronaldo was accused of fraud by the tax office last month following an investigation into his finances and tax returns.
He is not the first La Liga star to face such allegations. Barcelona rival Lionel Messi was handed a 21-month prison sentence for tax evasion, while Javier Mascherano received a 12-month suspended sentence, per the BBC.
It was also reported this year that Ronaldo had faced an allegation of rape earlier in his career.
German newspaper Der Spiegel reported in April, on the basis of evidence supplied by Football Leaks, that the forward paid a $375,000 settlement to a woman eight years ago after she said he raped her.
Ronaldo's lawyer Johannes Kreile said the player and his camp "categorically reject the accusations," but the sum was nevertheless reported to have been paid to keep the woman, named as "Susan K." in the report, quiet.