Spanish law states that a sentence of under two years for a first offense can be served on probation.
Mourinho's representatives were not immediately available for comment. Manchester United and the Spanish tax agency both declined to comment.
Spanish prosecutors filed a claim against Mourinho last year on two counts of tax fraud dating back to when he coached Real Madrid. Mourinho left Real Madrid in 2013 to manage English club Chelsea for a second spell before signing with United in 2016.
Spanish tax authorities had said the Portuguese manager owed 3.3 million euros. Prosecutors said he had failed to declare revenues from his image rights in his Spanish income tax declarations from 2011 and 2012, "with the aim of obtaining illicit profits".
They said Mourinho had already settled a previous claim relating to his Spanish taxes after a 2014 inquiry, which resulted in a penalty of 1.15 million euros. But tax authorities later found that some of the information presented in that settlement was incorrect, the prosecutors said.
The Mourinho settlement comes amid a lengthening list of tax fraud cases involving soccer stars in Spain.In June, former Real Madrid player Cristiano Ronaldo reached a similar deal with the Spanish tax authorities to serve two years in prison and pay a 18.8 million euro fine in a tax evasion case.