Tiffany Haddish says she turned down an offer to host a Grammys pre-show -- and it's all because the org was trying to make her foot the bill ... for everything.

The comedic actor says she was offered the hosting gig for the Recording Academy's 3-hour pre-telecast ahead of the main show in January, but when she was told she wouldn't get paid ... it gave her pause. Then she was told everything else would come out of her own pocket as well -- including hair, makeup and wardrobe costs -- so Tiff told them to kick rocks.

She tells Variety, "I don’t know if this might mean I might not get nominated ever again, but I think it’s disrespectful." Tiffany is, in fact, up for a Grammy this year for her Netflix comedy special, 'Black Mitzvah' ... she was nominated last year too for a spoken word project.

The Recording Academy tells Variety that because the pre-telecast isn't put on by CBS but, rather, themselves (a non-profit), they say it's normal for the hosting job to be pro-bono -- and apparently has been for a while. They also said Tiff's decision would have no bearing on any future nominations whatsoever.

That still didn't stop TH from openly criticizing them though -- she says, "How many other people have they done that to? It’s like a guy asking you on a date but telling you that you have to pay for it."

This is just the latest controversy to dog the Grammys this year ... coming a couple weeks after The Weeknd's outrage at being snubbed, and his allegations there were shady politics behind it.