How to fill out a W-4 form

2 mins read by Rachel Carey Last updated November 27, 2024

When you start a new job in the US, one of the first things you’ll usually be asked to do by your employer is to fill out Form W-4. Once you know what this IRS document is, why it’s necessary, and how to fill it out, doing so can be straightforward and stress-free.

What is a W-4 form?

As explained at the top of the W-4 form itself, this IRS tax document is completed “so that your employer can withhold the correct federal income tax from your pay.” Also known as an ‘Employee’s Withholding Certificate,’ it’s not sent directly to the IRS. Similarly to the W-9 form, it’s an evidence return provided to your employer.

The more accurately you fill out your W-4, the less likely you will owe (or be owed) money when annual income taxes are filed.

Every new employer should ask you to fill one out, but you should also update your existing W-4 with your current employer if you think the amount of tax that needs to be withheld has changed or if it was incorrect in the previous tax year. For example:

  • Your past tax return saw you owing a large balance or due a large refund

  • Your income has changed

  • You’ve received a promotion or a raise

  • You’ve stayed with your employer but changed job role

  • You have a new dependent

  • You have a new job (e.g., part-time employment on the side that will increase your overall income)

It’s important to note that if you start a new job in the middle of the year, having not been previously employed, you can save money on your taxes by requesting in writing that your employer uses the part-year tax withholding method. You are only eligible for this method if you were employed for no more than 245 days during the year.

How to fill out a W-4 form

Since the W-4 was changed in 2020, it’s more understandable and offers employees more straightforward and precise guidance on what they need to include. If you have not filled out a W-4 form since 2020, you may find the process has changed – but you’ll likely find it’s changed for the better.

W-4 forms can be submitted to your employer either electronically or physically – be sure to check your employer’s preference if they don’t indicate it to you. The most current revision of Form W-4 is available in a downloadable PDF format from the IRS website, and it consists, in total, of five steps:

  • Step 1: Enter personal information – During this step, you’ll share your full name, address, and Social Security Number (SSN). Then, you’ll tick the correct box to indicate whether you’re single, married but filing separately, married filing jointly, a qualifying surviving spouse, or a head of household (unmarried, paying more than half of household costs for you and another qualifying individual).

  • Step 2: Multiple jobs or spouse works – This step only needs to be completed if it applies to you. It will apply if you either hold more than one job at a time or are married filing jointly, and your spouse also works.

    • Step 2(b): Multiple Jobs Worksheet—This section on Page 3 will help you to calculate the total extra tax for all of your jobs in the confines of a single W-4. If this sheet is completed and option 2(b) is selected, the final determined sum should be noted in Step 4(c).

  • Step 3: Claim dependent and other credits – This step asks you to indicate how many children or other dependents you have (if your total income will be under $200,000 as a single filer or $400,000 if married and filing jointly).

  • Step 4 (optional): Other adjustments – This step is where you’ll have a chance to indicate any other adjustments that should be accounted for when the withholding amount is being determined. Step 4(a) asks about other income not earned from jobs. Step 4(b) asks about deductions other than the standard deduction. Step 4(c) is an opportunity to list any additional tax you want to be withheld (see Step 2(b).

    • Step 4(b): Deductions worksheet – This is a section on Page 3 where you can list any itemized deductions you want to make.

  • Step 5: Sign here – All you’ll need to do in Step 5 is sign and date the form, confirming that everything you’ve detailed is, to the best of your knowledge, correct and accurate.

Complying with IRS tax regulations can be time-consuming and complex. But, when you break the form down step-by-step and take those steps one at a time, it becomes simplified.  

What happens if I don’t fill out my W-4 form?

If you fail to fill out your W-4 and send it to your employer, you may not pay enough federal income tax throughout the year, resulting in unexpected fees later.

Alternatively, on the other end of the spectrum, your employer may withhold more income tax than they need from you by working to defaults – the highest rate for single filers, with no other adjustments.

What is the W-4 Form used for?

A W-4 tells an employer about an employee’s tax filing status so that they can accurately determine how much of their paycheck to withhold for federal income tax.

When this determination is correct, tax season becomes smoother, reducing the possibility of discrepancies between what’s due and what’s been paid across the year.

If you still have questions about tax paperwork or any other aspect of your financial life, connect with a professional financial advisor who can point you in the right direction. 

Senior Content Writer

Rachel Carey

Rachel is a Senior Content Writer at Unbiased. She has nearly a decade of experience writing and producing content across a range of different sectors.