What Changed in 2020 — and Why
The W-4 form your employer has on file determines how much federal income tax gets withheld from every paycheck. Get it right and you break even: no large refund (which means you overwitheld — effectively giving the IRS an interest-free loan all year) and no surprise balance due (which can trigger an underpayment penalty). The problem is that millions of employees are still on a pre-2020 form.
The old W-4 asked you to claim "allowances." More allowances equaled less withholding. The math was counterintuitive, and two-earner households routinely underwitheld because each employer withheld as if that job were the household's only income. The IRS eliminated allowances entirely when it redesigned the form; Form W-4 now uses five plain-language steps tied to your actual income, dependents, and deductions.
If you submitted a W-4 before 2020 and never updated it, your employer continues to honor it under the old rules. It isn't invalid — but running through the new version typically gets you closer to zero.
Step 1 — Personal Information (Required)
Enter your legal name, address, and Social Security number. Select your filing status:
- Single or Married filing separately
- Married filing jointly or Qualifying surviving spouse
- Head of household
Filing status determines your standard deduction and bracket width. Selecting the wrong status — the most common example is a married employee who selects Single — causes persistent over-withholding that won't resolve until the form is corrected.
Step 2 — Multiple Jobs or Spouse Works (Complete if Your Household Has More Than One Income)
Step 2 is the most commonly skipped step and the biggest source of under-withholding. When you skip it, each employer withholds as if that job were your only income — but your combined household income may push you into a higher bracket, and neither employer's withholding accounts for the difference.
Complete Step 2 if you work two or more jobs simultaneously, or if you're married filing jointly and your spouse also works.
Three options are available:
- Option A (most accurate): Use the IRS Tax Withholding Estimator, which calculates the precise additional withholding needed across all jobs, then enter the recommended per-pay-period amount in Step 4(c).
- Option B: Complete the Multiple Jobs Worksheet on page 3 of the W-4 instructions.
- Option C: Check the box if there are exactly two jobs in the household paying roughly the same amount — this triggers a flat increment without the full worksheet.
Option A takes about 15 minutes and handles unequal salaries, investment income, and other variables the worksheet can miss. For a two-earner household earning different amounts, it can prevent a $2,000–$4,000 surprise at filing.
Step 3 — Claim Dependents (Optional)
Step 3 lets you credit qualifying dependents directly against your withholding so the tax benefit flows throughout the year — you don't have to wait until April to receive it as a refund. The credit amounts are printed on the current W-4 instructions reflecting any 2026 adjustments from the One Big Beautiful Bill Act. For the full breakdown of how OBBBA adjusted dependent credits and income brackets, see the individual tax changes guide.
Income ceiling: this step applies only if your expected income from this job is $200,000 or less ($400,000 or less for married filing jointly). Above those thresholds, skip Step 3 and use the IRS Estimator to account for credits.
Step 4 — Other Adjustments (Optional)
Three sub-lines address income or deductions outside of regular wages:
4(a) — Other Income: Enter expected income not subject to withholding — freelance work, rental income, interest, dividends. Adding it here covers the tax proactively instead of owing the full amount in April.
4(b) — Deductions: If you plan to itemize or claim above-the-line deductions that exceed your standard deduction, enter the excess here to reduce withholding. Above-the-line deductions include contributions to a SEP-IRA, solo 401(k), HSA, and deductible student loan interest. Use the Deductions Worksheet on page 3 of the instructions.
4(c) — Extra Withholding: Request a specific flat dollar amount withheld each pay period. Useful if you're catching up after under-withholding earlier in the year, or if Option A of Step 2 directed you to add a per-period amount here.
Step 5 — Sign and Date (Required)
Your signature certifies the form's accuracy under penalty of perjury. Submit the completed form to your employer's HR or payroll department — not to the IRS. Employers must implement the new withholding starting with the first or second full payroll period after receipt, per IRS Publication 15-T, which governs employer withholding tables and procedures.
Why 2026 Is a Good Time to Review
The One Big Beautiful Bill Act changed standard deduction amounts, income brackets, and family credit amounts for tax year 2026. A W-4 you filed before those changes took effect may yield slightly off withholding. See the individual tax changes guide for specifics on what changed.
Beyond OBBBA, other common triggers for updating your W-4:
- New job or second job: Step 2 must be re-run for every new income source.
- Marriage or divorce: Your filing status changes, and combined (or newly solo) income affects every step.
- A child born or adopted: Adds a qualifying dependent to Step 3 and may lower your withholding for the rest of the year.
- Started a side hustle or rental: Step 4(a) captures that income so you're not blindsided in April.
- Bought a home: New mortgage interest and property tax deductions may let you reduce withholding via Step 4(b).
- Maxing a retirement account: SEP-IRA, solo 401(k), or HSA contributions may create above-the-line deductions that go in Step 4(b).
Doing this now — mid-year — leaves enough payroll periods to correct any gap before December 31. The mid-year tax planning checklist covers other moves worth making before year-end.
Under-Withholding Penalty — What the Rules Actually Require
The IRS charges an underpayment penalty only when both conditions are met:
- You owe more than $1,000 after credits and withholding, AND
- Your withholding plus any quarterly estimated tax payments covered less than 90% of this year's tax — OR less than 100% of last year's total tax bill.
The second condition — the prior-year 100% safe harbor — is the practical backstop for most employees. If your withholding at least equals last year's total tax, no penalty applies even if you owe in April. For business owners who combine a W-4 salary from an S-corp with pass-through income, the employer payroll taxes guide covers the full estimated-tax compliance picture.
A large April refund is the mirror image of under-withholding: you're paying the right tax, just sending it to the IRS months early instead of when it's due. Neither extreme is ideal. The IRS Tax Withholding Estimator targets a balance due of roughly zero — close enough to avoid a penalty without over-lending the government your cash.
