It is not clear, however, if the 48-year-old Cristina will take advantage of the ruling, issued "strictly on security grounds", when she heads to the Palma de Mallorca court on the morning of February 8.
Judge Juan Castro's decision, which is in line with police advice, allows the princess to drive all the way to the court rather than walking the last steps from the main street to the door of the court.
Cristina will be the first direct member of the Spanish royal family in modern times to face court as a suspect when she answers the summons in a scandal that has plunged the royals into crisis.
Lawyers defending the princess, known as the Infanta, insist she is innocent of accusations of tax fraud and money-laundering.
The case is linked to the business affairs of Cristina's husband, former Olympic handball player Inaki Urdangarin, who is himself under investigation for alleged embezzlement of public funds.
Cristina has been made a formal suspect in the case, but neither she nor Urdangarin have so far been charged with any crime.
Urdangarin has testified twice at the court in the past two years. Despite a court ruling allowing him to drive to the entrance, he chose each time to walk the final steps, in the same way as any other suspect.
The fraud scandal has been a major blow to the royal family's prestige.
King Juan Carlos, 76, had long been respected for helping guide Spain to democracy after the death in 1975 of General Francisco Franco.
But the fraud case, as well as outrage over a luxury African elephant-hunting safari he took in 2012 as his subjects suffered in a recession, have damaged his reputation.