Filling out a W-4 might seem like a quick, one-time task you complete on your first day of a new job—but in reality, it directly impacts your paycheck, your tax bill, and how smooth (or stressful) tax season feels. If your W-4 isn’t filled out correctly, you could end up: Owing money at tax time Getting a refund you didn’t need Or dealing with inconsistent cash flow all year Let’s break down the 7 most common W‑4 mistakes—and what you should do instead. Mistake #1: Choosing t