What finish should I use for ceiling paint that doesn't yellow?

Matte or satin finishes are your best allies for avoiding yellowing on a ceiling. Glossy paints tend to yellow faster, especially over time and with light exposure. Go for a good quality paint, preferably water-based rather than oil-based, and make sure it's specifically formulated for ceilings and anti-yellowing - it's usually indicated on the can.

You can also look into high-end acrylic paints or formulas specifically designed anti-UV - they really yellow way less over time than standard paints. One other smart thing: avoid applying directly to a ceiling that's already stained or yellowed without priming first, otherwise you risk it showing through the new paint. And if you go with satin instead of matte, you'll get better durability without sacrificing aesthetics too much.

Before you paint, make sure your ceiling is really clean and there's no smoke marks or dust that'll oxidize over time - that's often what causes the yellowing, not just the paint itself. After that, a quality white primer before your matte finish will make a big difference, it blocks a lot of grime that would come back up otherwise.

It's really the quality of the paint that matters more than the finish - a good white acrylic from a recognized brand (even if it's glossy) will yellow way less than cheap basic matte stuff. The guys above are right about cleaning the ceiling, but they're forgetting that if you already spot yellowing before painting (nicotine, humidity), a primer undercoat will block that way better than any finish.