Ronaldo is at the Confederations Cup in Russian Federation, playing for Portugal.
The cases are about the profits made from image rights, not salaries from their clubs.
The Brazilian's proposed move to Madrid from Santos fell through and in 2013 he ended up singing for Real's fiercest rivals Barcelona.
Representatives for Ronaldo declined to comment. A judge will then decide if they are grounds to charge him with a crime.
Prosecutors accuse the Portugal worldwide of evading tax via a shell company based in the British Virgin Islands and another in Ireland, known for its low corporate tax rate.
Ronaldo has denied any wrongdoing.
But the situation has stuck in the craw for Ronaldo, leading the Portugal captain to tell those close to him that he wants to quit the club and the country.
The Spanish prosecutor says the Real Madrid forward knowingly used a business structure to hide his image rights income in Spain between 2011 and 2014. "To this date, neither the Spanish tax authorities, nor the public prosecutor have contacted Jose Mourinho or his advisers who were hired for the inspection process", the statement from Gestifute Media read.
The hearing will take place at 09:00 GMT on July 31 in a court at Pozuelo de Alarcón, in the suburbs of Madrid, according to Spanish press reports.