Today's ruling comes just two days after Silvio Berlusconi said he would not run for a fourth term as Prime Minister.
He remains the leader of the centre-right People of Freedom party that he founded.
In February, a corruption case involving Mr Berlusconi was thrown out because it expired under the statute of limitations.
He is also facing separate charges of sex with an under-age prostitute.
Media reports in Italy suggest lawyers for Silvio Berlusconi are to appeal against his jail sentence for tax fraud.
The former Prime Minister of Italy Silvio Berlusconi has been sentenced to four years in prison for his part in a tax evasion scheme.