Princess Cristina will become the first member of the Spanish royal family to stand trial when court proceedings open Monday in a tax fraud case.
Cristina, 50, the sister of King Felipe VI, was stripped of her duchess title over the embezzlement charges, which she faces as an accessory to her husband Inaki Urdangarin, 47.
Urdangarin, a former Olympic handball player, is accused of embezzling about 6 million euros (6.8 million dollars) in public funds through a charity, the Noos Institute, which he ran from 2004 to 2006.
Cristina allegedly helped him withhold income tax in 2007 and 2008.
Urdangarin's business partner Diego Torres is among the total of 18 accused in the case.
Cristina received the title of duchess from her father, then-king Juan Carlos, when she married Urdangarin, in 1997. Urdangarin was named the duke of Palma de Mallorca at the time, and has been stripped of that title.
Prosecutors are seeking a 20-year prison sentence for Urdangarin.
The defence is expected to ask for the case against Cristina to be dismissed, arguing that both the prosecution and the tax authorities were opposed to the indictment against her.
They will also say that the charges were based solely on the actions of the trade union Manos Limpias (Clean Hands), which fights corruption and is acting as joint plaintiff in the case. It is seeking eight years and a fine of 2 million euros against her.