Like all other new prisoners, he will initially be housed in the high-security reception unit, where he can remain up to 30 days, the Prison Administration said.
At the end of the reception period, which is also used for prisoner evaluation, he will get a personal plan which will determine how he will serve the rest of his sentence.
Bavčar had been expected in prison since the Ljubljana Higher Court upheld in May guilty rulings against him and the Sušinski brothers, Nastja and Kristjan, in a retrial over a 2007 chain sale of a 7.3% stake in the Istrabenz conglomerate.
Bavčar, an independence-era interior minister who went to become one of the most powerful business executives before the recession hit the country's economy, was found guilty of money laundering.
He had managed to avoid serving prison after the original ruling from 2013 by citing health concerns, but this time he tried other avenues since new legislation made it more difficult to avoid prison due to health reasons.
Neither the District Court nor the Higher Court accepted his grounds for deferral.