They claim that Mourinho - who took over at United previous year - failed to declare income of 1.6 million euros in 2011 and 1.7 million euros in 2012.
A €120m bid has been discussed between PSG and Ronaldo's agent Jorge Mendes as the former Sporting CP man plots his next career move should he leave Madrid.
The Portugal superstar is believed to have taken an "irreversible" decision to leave Real Madrid this summer.
The agency published copies of the certificates.
In July 2014 he was told he was being investigated and a year later he signed an agreement acknowledging unpaid tax on image rights, agreeing to pay a 1.14m euros penalty. A judge will then decide if they are grounds to charge him with a crime. He was in charge of Real Madrid from 2010 to 2013 and the prosecutor is alleging Mourinho that he did not declare image rights income to get "illicit benefit", according to the BBC.
Ronaldo has denied any wrongdoing, while Real Madrid released a statement saying they had "full confidence" in their player and were "absolutely convinced that (he) will prove his total innocence".
Their report suggesting this story will predictably end with Ronaldo resolving his tax problems in Spain and staying with the club he has guided to back-to-back Champions League titles over the last two seasons.
Di Maria, who now plays for French club Paris Saint-Germain, will likely not serve any prison time because sentences of less than two years for first-time offenders are usually suspended in Spain. Prosecutors accuse Ronaldo, who is the world's highest paid athlete according to Forbes magazine, of evading tax via two companies based in the British Virgin Islands and Ireland.
This is similar to deals struck with the Spanish taxman by fellow Argentinians Javier Mascherano and Lionel Messi a year ago.
In 2016, Barcelona defender Javier Mascherano received a one-year suspended prison sentence for tax fraud while Barca superstars Lionel Messi and Neymar are both now awaiting court decisions.
Senate GOP health bill would reshape Obama law
The Senate measure would also seek to phase out the program's expansion - although at a more gradual rate than the House version. He said "small tweaks" during the upcoming debate "cannot change the fundamental meanness at the core of this legislation".