Ronaldo is alleged to have defrauded Spanish authorities of 14.7m euros between 2011 and 2014.
In a statement, the prosecutor's office said Ronaldo had knowingly used a "business structure" created in 2010 to hide his income in Spain from his image rights.
The lawsuit is based on a report sent to the prosecutor's office from Spain's tax agency AEAT, it said.
More to follow...