The platinum-selling rapper, whose real name is Jeffrey Atkins, turned to look at his wife after a judge read the sentence in a Newark federal courtroom Monday.
He admitted in March that he failed to pay taxes on more than $3 million that he earned between 2004 and 2006 while he lived in Saddle River.
Ja Rule was sentenced in New York City last month to up to two years in prison after he pleaded guilty to attempted criminal weapon possession. The case stemmed from a gun found in his car in 2007.
The majority of the sentences will be served at the same time.