This past year, Simon reportedly made $36 million for doing "Idol" . . . and according to Britain's "The Guardian" newspaper, Fox has offered Simon, quote, "three or four times that amount" to stay on the show.

That means his next contract could pay him between $100 million and $144 million . . . PER YEAR. (!!!)

Not surprisingly, Fox won't comment on any of this. And Simon's people haven't, either.

As ridiculous as those numbers sound, "Idol" is a HUGE moneymaker. It's the highest-rated show on TV . . . and it generates an estimated $900 million a year for Fox.

Just to be clear, Simon IS signed through next season . . . (--the show's NINTH.) His contract is up after that . . . in May of next year.

(--We'll keep you posted on this . . . but for now, you should be skeptical of this report. The "Guardian" says they spoke with a "source" close to the situation . . . but we all know how reliable those British newspapers can be.)