The charges are from his nine years at Real Madrid, whom he left for Italian club Juventus last summer.
Cristiano Ronaldo and girlfriend
Cristiano Ronaldo has accepted a £17m fine after pleading guilty to tax fraud in Madrid on Tuesday morning.
The judge denied Ronaldo's request to appear by video or enter the building by car and arrived at the courthouse with his girlfriend Georgina Rodriguez.
His lawyers had argued that given his fame, avoiding the main entrance was needed for the player's security.
Ronaldo spent around 45 minutes in court and, after formally accepting the deal offered by prosecutors, signed the agreement to pay the huge fine.
The deal, agreed in advance, includes a 23-month jail sentence.
But in Spain, convicts do not usually do time for sentences under two years.
The charges are from his nine years at Real, whom he left for Italian club Juventus last summer.
MySportDab report Prosecutors accused him of four counts of tax fraud from 2011-14 worth 14.7m euros (£12.9) and using shell companies outside Spain to hide income made from image rights.