In early May, the Supreme Court rejected Cacic's appeal to a Zagreb County Court ruling sentencing him to 22 months' imprisonment in accordance with a Hungarian court ruling. He was served with a court order to serve his prison term on June 4.
He will spend several weeks at Remetinec for observation, after which experts will decide where he will serve the rest of the sentence, most probably in a low security facility.
After serving half the sentence, Cacic can apply for early release.
He has also been banned to drive for three years.
Cacic was first sentenced in Kaposvar, Hungary last November, after which he resigned to all government posts and requested to serve the sentence in Croatia.
Cacic, who was also at the helm of the Croatian People's Party (HNS), said earlier he wished to start serving his sentence as soon as possible and arranged with the judge in his case that he would report to Remetinec today.