Most of us know the rule of thumb when it comes to sunscreen: Wear it all day, every day, even if you’re indoors. The topic of wearing sunscreen with makeup — especially foundation — is not so cut and dry, though. Is the SPF in your foundation enough? Should you apply your sunscreen under your makeup? How can you reapply sunscreen over foundation? To answer these questions, we consulted with Dr. Bruce Katz, a New York City-based board-certified dermatologist. Keep scrolling for his safe sun tips.