Reports have since suggested that Ronaldo may have made a decision to leave Real Madrid amid claims he is angry at his treatment by Spanish authorities and that Portugal has launched its own tax fraud probe into the world's highest paid athlete.
"I hope [he'll return]", the former England global is quoted as saying by the Manchester Evening News at an event in Belfast, as reported by Goal.
Other clients of Mendes who have ended up in Spain include the Portuguese full-back Fabio Coentrao - on the verge of joining Sporting Lisbon on loan from Real Madrid - and Colombian striker Radamel Falcao, now with Monaco but formerly at Atletico Madrid.
In three years with Real Madrid, Mourinho won La Liga in 2012 and the Spanish Cup in 2011.
Both Ronaldo and Mourinho are represented by Portuguese agent Jorge Mendes.
The statement said that the Spanish government, through tax authorities, "issued a certificate in which it attested that he had regularized his position and was in compliance with all his tax obligations".More news: Oil tanker flips and explodes, killing over 100 in Pakistan
Di Maria, 29, made a deal with authorities to avoid a trial at the Spanish Supreme Court - which found Lionel Messi guilty of similar crimes a year ago. A judge will then decide if they are grounds to charge him with a crime.
A statement issued by the section for economic crimes of Madrid's provincial state prosecutor's office said its investigations indicated that Mourinho committed tax fraud in 2011 and 2012.
Ronaldo's trouble coincided with the same Madrid-based prosecutor's office accusing Mourinho of two counts of tax fraud.
They claim that Mourinho, who took over at United previous year, failed to declare €3.3 million (RM15.77 million) during his time in the Spanish capital - €1.6 million in 2011 and €1.7 million in 2012.
The Argentinian is unlikely to spend any time behind bars as sentences of under two-years are usually suspended, providing the convicted has no criminal record.
The 29-year-old and his father Jorge Horacio Messi were found guilty of using offshore companies to avoid paying taxes on €4.16 million of Messi's income earned from his image rights from 2007 to 2009.
Angel Di Maria has been handed a one-year prison sentence and fined £1.76 million after admitting tax fraud.