Our music industry sources tell us Mariah still pulls in big bucks on licensing and commercial deals for the classic. While we're told she's only making a fraction of a cent every time someone streams "All I Want For Christmas Is You," the fractions add up to seven figures and counting, considering the popular Xmas track has over 1 billion streams just on Spotify.

One source who manages artists tells us singers typically make between .003 to .004 of a dollar per single stream ... and in Mariah's case, that would work out to between $3,249,600 and $4,332,800 just on Spotify alone ... and the figure will only grow.

Mariah's 1994 song is hugely popular around the holidays and as another source put it ... "Mariah can sit on her a** for the rest of her life and ONLY promote AIWFC and still be a millionaire."

What's more, the numbers don't even take into account streams on other platforms, including Apple Music. We reached out to Apple for an all-time count on 'AIWFC' streams ... so far no word back.

Streaming platforms weren't around when Mariah first launched the song, and it's pre-streaming days when she would've made the most money in sales ... but that doesn't mean today's numbers translate to chump change.