One of various corruption scandals during the economic crisis
The case is one of various financial corruption scandals affecting the royal family and major political parties and a leading union, during the economic crisis, when many Spaniards have lost jobs or had to tighten their financial belts.
Princess Cristina's testimony comes as a new report by the European Commission shows that 95% of Spaniards say that corruption is widespread in the nation.
The royal household two years ago excluded Princess Cristina and her husband from representing Spain at official functions, like one in Madrid this week, when the King, Queen Sofia, Crown Prince Felipe and his wife, Princess Letizia, welcomed the foreign diplomatic corps.
But some Spaniards say the princess is still getting special treatment.
"It's great they're finally bringing preliminary charges," said student Mariana Moragrega, outside the royal palace in Madrid, on Friday. "But considering she's the King's daughter, she'll be very protected, and won't go to jail."
Spanish media reports said the judge is not expected to immediately issue a decision on whether to proceed with the case or to drop the charges against the princess.