According to reports, he is set to face charges for an alleged 14.7 million euros of tax evasion from 2011 to 2014.
The world's highest-paid sports star had previously said he was not anxious about tax investigations as he had nothing to hide.
Spanish prosecutors on Tuesday accused the forward of defrauding the country's tax authorities of 14.7m euros in relation to income generated from image rights.
But Ronaldo's good vibes likely came to an end this week, after Spanish prosecutors charged the 32-year-old with four counts of tax evasion. A Barcelona court found that the Messis had evaded tax on Lionel's image rights, with more than €4m (£3.5m) owed in back payments.
The prosecutor also alleged that the Portuguese falsely reported income as coming from real estate.
A spokeswoman for Gestifute, the agency that represents Ronaldo, declined to comment to Bloomberg.
The Gestifute management company, which is owned by Ronaldo's agent Jorge Mendes, released a statement on 13 June denying that Ronaldo had concealed his income from Spanish authorities.
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In addition, they say he only declared 11.5 million euros of Spanish-related income from 2011 to 2014, while what he really earned during that time was close to 43 million euros.
Messi was handed a 21-month suspended jail sentence past year after being found guilty of similar offences, while his Barcelona teammate Neymar will face trial over alleged irregularities in his 2013 transfer from Brazilian club Santos. However, he too, will not see a day in prison.
Ronaldo reportedly earned $93 million previous year in salary, endorsements and other bonuses.
The 32-year-old is the reigning Ballon d'Or and FIFA World Player of the Year victor.
The Real star - his club's all-time leading scorer - has also enjoyed a stellar 12 months on the field, guiding Portugal to Euro 2016 success last summer and helping his club win the Spanish league and Champions League in the 2016/17 season.
Ronaldo and the rest of Portugal's team are flying to Russian Federation to play at the Confederations Cup as European champions.