Find the right withholding to break even at tax time — no nasty surprise bill, no oversized refund.
Your W-4 tells your employer how much federal income tax to withhold from each paycheck. The IRS redesigned the form in 2020 — it no longer uses "allowances." Instead, it uses dollar amounts in specific steps.
A big refund sounds nice, but it just means you gave the IRS an interest-free loan all year. A big tax bill at filing means you underpaid and might owe a penalty. Aim to land within a few hundred dollars of zero.
If you or your spouse have multiple jobs, tax withholding gets complicated because each employer only knows about one income. Step 2 on the W-4 accounts for this — the IRS withholding estimator is the most accurate tool for this scenario.
Enter the dollar amount of your credits (e.g., $2,000 per qualifying child). This reduces your withholding directly.
Use Step 4(a) for other income not subject to withholding. Use 4(b) for extra deductions. Use 4(c) to add a flat dollar amount of additional withholding per paycheck if you want to make sure you don't underpay.
After any major life event: marriage, divorce, new child, second job, large investment income, or purchasing a home. Even if nothing changes, checking once a year is good practice.