Jose Mourinho was accused by Spanish authorities of failing to pay €3.3 million ($3.7 million) in taxes at Real Madrid as star player Cristiano Ronaldo was summoned to appear before a judge in July.
The 54-year-old Mourinho, who coached Real Madrid from 2010 to 2013, was accused of "two offences against the public treasury," the prosecutor's office said in a statement.
Prosecutors claim that the Portuguese manager — who took over at Manchester United in 2016 — failed to declare income of €1.6 million in 2011 and €1.7 million in 2012.
Real Madrid star Ronaldo was last week accused of evading €14.7 million through offshore companies and will appear before a judge on July 31, judicial sources said.
The 32-year-old Portuguese star is facing four charges of fraud through offshore companies between 2011 and 2014.
The hearing will take place on July 31 in a court at Pozuelo de Alarcon, in the suburbs of Madrid, according to Spanish press reports.
Prosecutors accuse the Portugal international of evading tax via a shell company based in the British Virgin Islands and another in Ireland, known for its low corporate tax rate.
In addition, they say he only declared €11.5 million of Spanish-related income from 2011 to 2014, while what he really earned during that time was close to €43 million.
And finally, they accuse him of "voluntarily" refusing to include €28.4 million in income linked to the sale of his image rights for the 2015 to 2020 period to a Spanish company.
The four-time world player of the year, who said last week his "conscience is clear", is threatening to leave Real Madrid over the affair.
Ronaldo is currently on duty for Portugal at the Confederations Cup in Russia which ends on July 2.
Both Ronaldo and Mourinho are clients of football super-agent Jorge Mendes, who has been summoned to appear before the court at Pozuelo de Alarcon on June 27.
In three years with Real Madrid, Mourinho won La Liga (2012) and the Spanish Cup (2011). He also won the Champions League twice with Porto (2004) and Inter Milan (2010).
The football world in Spain has been rocked by charges of tax evasion or corruption pressed against some of its top stars.
Barcelona star Lionel Messi was sentenced to a 21-month jail sentence and €2.09 million fine last year for tax fraud.
The prison term will be suspended as is common in Spain for first offences for non-violent crimes carrying a sentence of less than two years.
The 29-year-old and his father Jorge Horacio Messi were found guilty of using companies in Belize, Britain, Switzerland and Uruguay to avoid paying taxes on €4.16 million of Messi's income earned from his image rights from 2007-09.
Former Barca defender Javier Mascherano also agreed a one-year suspended sentence with authorities for tax fraud in 2016.
Meanwhile Brazil star and Barcelona forward Neymar and his parents are due to stand trial for alleged corruption over his transfer from Santos in 2013.