How do I set my W-4 withholding so I don't owe or overpay at tax time?

The goal of a W-4 is to have your employer withhold close to your actual tax — not a penny more or less. The redesigned W-4 doesn't use "allowances" anymore; instead you account for multiple jobs, a working spouse, dependents, and other income in Steps 2–4. The most accurate approach is the IRS Tax Withholding Estimator, which tells you exactly what to enter, including any extra dollar amount per paycheck on line 4(c). Revisit your W-4 after any big change: marriage, a new baby, a raise, a second job, or a spouse starting work. Aim for a small refund or a small balance due. If you consistently owe or get huge refunds, your W-4 is mistuned. For high earners with RSUs or bonuses, fine-tune at wealthserene.com/tools/w2-optimizer.