The former Real Madrid star accepted the punishments last month having pleaded guilty to four breaches of tax laws in Spain between 2011 and 2014.
Ronaldo's breaches related to taxes owed on image rights income.
The final deal - which on Thursday received the necessary approval of Hacienda, the Spanish treasury - sees an acceptance that $A9 million is owed in taxes, with the remaining $A20 million including court fees and fines in interest.
The 33-year-old, who signed a four-year contract with Serie A champion Juventus earlier this month, had denied the charges when he appeared before a Madrid court last July.
But Hacienda's approval of the agreement means the long-running saga is now effectively over.