How to Fill Out a W4 Form: Step-by-Step Instructions

Thapana Onphalai / Getty Images/iStockphoto

Commitment to Our Readers

GOBankingRates' editorial team is committed to bringing you unbiased reviews and information. We use data-driven methodologies to evaluate financial products and services - our reviews and ratings are not influenced by advertisers. You can read more about our editorial guidelines and our products and services review methodology.

20 Years
Helping You Live Richer

Reviewed
by Experts

Trusted by
Millions of Readers

Ever looked at your paycheck and wondered why your take-home pay seems off? It might have something to do with your W-4 form. If you’re starting a new job, picking up a side hustle or going through a life change — this form matters more than you might think.

In this guide, we’ll walk you through how to fill out a W-4, what each section means and how to make sure your tax withholding matches your real-life situation. That way, you can avoid tax surprises and keep more money in your pocket when it counts.

What Is a W-4 Form and Why It Matters

The W-4 form is officially called the Employee’s Withholding Certificate, and it’s what you give your employer so they know how much federal income tax to take out of each paycheck.

Why it matters:

• Too little withheld? You might owe the IRS come tax season.
• Too much withheld? You’re essentially giving the government an interest-free loan.

Filling out the W-4 correctly means you’re more likely to break even at tax time and avoid both surprises and headaches.

What Is a W-4 Form?

In simple terms, the W-4 tells your employer how much federal income tax to withhold from your paycheck based on your:

• Filing status (like single or married)
• Dependents
• Other income or jobs
• Any extra money you want withheld

When to Fill Out a W-4:

• When starting a new job
• When your life situation changes (marriage, divorce, kids, second job)
• When you want to tweak your withholdings to better match your tax situation

Tip: You don’t have to fill out a new W-4 every year, but it’s smart to review it if your life or finances shift.

Step-by-Step: How To Fill Out a W-4 Form in 2025

Here’s a breakdown of what you’ll see on the W-4 and how to fill it out the right way.

Step 1: Enter Your Personal Information

Include your:

• Full name
• Address
• Social Security Number (SSN)
• Filing status (Single, Married filing jointly, or Head of household)

Choose your filing status carefully. It affects your standard deduction and how much tax gets withheld.

Step 2: Multiple Jobs or Spouse Works

This step helps avoid underpaying taxes if:

• You have more than one job
• Your spouse also works

You’ll have three options here:

1. Use the IRS Tax Withholding Estimator (most accurate)
2. Fill out the worksheet on Page 3 of the W-4
3. Check the box if you and your spouse each have one job and both earn about the same

Warning: Skipping this step is one of the most common reasons people owe taxes unexpectedly.

Step 3: Claim Dependents

If your income is below $200,000 (or $400,000 for joint filers), you can reduce your withholding by claiming child or dependent tax credits.

Here’s how:

• Multiply the number of qualifying children under 17 by $2,000
• Multiply the number of other dependents by $500

Add those numbers together and enter the total on Line 3.

Step 4: Other Adjustments (Optional)

This is where you can fine-tune your withholding based on:

• Other income (like interest, dividends, side gigs)
• Deductions (if you plan to itemize instead of taking the standard deduction)
• Extra withholding (if you’d rather have more taken out each paycheck)

Example: If you freelance on the side and want to cover that tax upfront, enter an estimated annual amount under “Other income.”

Step 5: Sign and Date

Once you’re done, sign and date the form. Give it to your employer, not the IRS.

Tip: Review the form for accuracy before submitting. Small errors, like checking the wrong box, can throw off your entire withholding.

Tips for Filling Out a W-4 Correctly

Do you need some tips to help fill out your W-4 correctly? These tips may help:

1. Use the IRS tax withholding estimator for precise calculations: Everyone has access to the IRS tools on their website. You can visit the irs.gov/withholding for a personalized estimate. Enter your income, filing status and deductions to help calculate the right amount to withhold. 
2. Adjust for multiple jobs or dual income households: If you or your spouse have multiple jobs, use step two of your W-4. You can check the box, use the IRS estimator, or complete the worksheet to account for the additional income.
3. Update your W-4 regularly if you experience life changes:  If you have a major life change, like marriage, divorce, income changes, or a new job, make certain your W-4 reflects these changes. 
4. Avoid common mistakes: Don’t forget to include second jobs or side hustles. Also, don’t forget to include other taxable income like interest and dividends. 

Example: Completed W-4 Form (2025)

Let’s walk through an example so it all comes together. Imagine you’re:

• Filing as single
• Working one job
• Claiming two children under 17

Here’s how your form might look:

• Step 1: Your name, SSN and “Single” checked
• Step 2: Leave blank (only one job)
• Step 3: $4,000 entered (two children ?– $2,000)
• Step 4: Leave blank (no extra income or deductions)
• Step 5: Sign and date

This setup ensures your withholding reflects your household, so you’re not overpaying or underpaying on taxes.

W-4 Form vs. W-2 Form

How are the W-4 and W-2 forms different? These two forms often get mixed up, but they serve very different purposes. Here’s a side-by-side comparison:

When Should You Update Your W-4 Form?

You should update your W-4 whenever you want to increase or decrease your withholdings. You’ll also need to fill out a new form if the existing version of the form ever changes.

The IRS recommends reviewing your W-4 at least once a year, early in the year, and when the tax law changes.

You should also reassess your W-4 in the event of the following life changes: 

• Lifestyle: Change in marital status, purchase of a home, birth or adoption of a child, bankruptcy or retirement. 
• Itemized deductions or tax credits: Medical expenses, education credits, child tax credits, dependent care expenses, interest, charitable gifts or earned income credit change.
• Wage income: You or your spouse have a significant change in annual income. 
• Taxable income not subject to withholding: Interest income, dividends, capital gains, self-employment income or IRA distributions change. 
• Adjustments to income: IRA deduction or alimony expenses change.

Final Thoughts to GO: Take Control of Your Paycheck

Understanding how to fill out a W4 form can help you avoid big surprises at tax time, like owing money or getting a much smaller refund than expected.

Here’s a quick recap:

• Fill out your W-4 any time your life or income changes
• Use the IRS Estimator for more accurate results
• Double-check the form to make sure everything matches your current situation
• Don’t be afraid to update it mid-year, especially if you’ve started a side hustle or changed jobs

Being proactive with your W-4 gives you more control over your money, month after month.

Information is accurate as of April 23, 2025.

Editorial Note: This content is not provided by any entity covered in this article. Any opinions, analyses, reviews, ratings or recommendations expressed in this article are those of the author alone and have not been reviewed, approved or otherwise endorsed by any entity named in this article.

Share This Article: