The 33-year-old is accused of evading £5 million (€5.7 million) in taxes. He has denied the allegations.
This amount is likely to be only part of the striker’s fines over the case, which are expected to rise to around £16.8 million (€19 million) in total.
The Juventus footballer, formerly of Real Madrid, is accused of evading €14.7million in tax between 2011 and 2014.
Ronaldo is unlikely to go to prison as Spanish law states a sentence of under two years for a first offence can be served on probation.
The football star will be required to pay the £2.8 million (€3.2 million) fine plus the £5 million (€5.7 million) owed in taxes and £888,000 (€1 million) in accrued interest.
He will also pay 250 euros-per-day for the 48 months covering the prison sentence.
It is understood Ronaldo was keen to reach a settlement with tax bosses as he gets his finances in order following his shock £99 million move to Juventus earlier this month.
The 33-year-old had always fought the charges but decided to reach an agreement as he begin his new life in Italy.
He becomes the latest football star to be sentenced in a crackdown on tax evasion by Spanish authorities against high-profile footballers.
Barcelona legend Lionel Messi was handed a 21-month prison sentence in 2017 on similar tax fraud charges.
Under Spanish law, he was allowed to exchange the penalty for a fine.