What happens if I don’t submit a Form W-4 at all?

An employer is required to withhold tax as if filing single with no additional adjustments, which is typically the highest default withholding rate, generally resulting in a smaller paycheck than might otherwise apply.

How often should I update my Form W-4?

The IRS recommends reviewing a W-4 whenever a personal or financial situation changes, a new job, a change in marital status, a new dependent, or a significant shift in other income, since withholding should reflect current, not past, circumstances.

Can I claim exemption from withholding on my W-4?

Only when meeting specific conditions, generally having had no federal income tax liability in the prior year and expecting none in the current year. This exemption must be renewed each year by a specific deadline, and it’s not automatically continued from year to year.

Back to Glossary

Form W-4: telling your employer how much tax to withhold

Key takeaways
- Form W-4 tells an employer how much federal income tax to withhold from each paycheck.
- Getting it right matters, since incorrect withholding can lead to a large tax bill or an unnecessarily reduced paycheck throughout the year.
- Nonresident aliens follow special instructions when completing Form W-4, different from the standard version most employees use.
- A new W-4 should be submitted whenever a personal or financial situation changes significantly.
- Not submitting a W-4 at all results in withholding at the highest default rate, generally reducing take-home pay.

Form W-4 tells an employer exactly how much tax to withhold from a paycheck. Here’s how to fill it out correctly and when to update it.

What is Form W-4?

According to the IRS⁠(opens in new window), Form W-4 tells an employer filing status, adjustments for multiple jobs, credits, other income, and deductions, information used to calculate the correct amount of federal income tax to withhold from pay each pay period. Getting this right matters because it directly affects both paycheck size throughout the year and whether additional tax is owed or a refund received when filing an annual return.

How to fill out Form W-4 step by step

Complete Step 1 with personal information and filing status. This is required for everyone completing the form.
Complete Step 2 if there’s more than one job, or a spouse also works. This step helps ensure enough tax is withheld across all combined income.
Complete Step 3 to claim dependents, if applicable. This can reduce the amount withheld when qualifying for relevant tax credits.
Complete Step 4 for other adjustments, if needed. This covers other income, deductions, and any extra amount to be withheld.
Sign and submit the form to the employer. The form isn’t valid until signed, and it’s submitted directly to the employer, not to the IRS.

What’s different for nonresident aliens completing Form W-4

Nonresident aliens follow special instructions when completing Form W-4, outlined in IRS Notice 1392, that differ in some specific respects from the standard instructions most employees use. This distinction matters because using the standard instructions without adjustment can result in incorrect withholding for someone who’s a nonresident alien for tax purposes, making it worth confirming specific tax residency status, as covered under IRS Publication 519, before completing this form for the first time.

What Form W-4 means for people sending money internationally

Getting W-4 withholding accurate directly affects how much of a paycheck actually reaches a bank account to work with, including how much can be sent to family abroad on a regular basis. Withholding too much means smaller paychecks throughout the year in exchange for a larger refund later, while withholding too little means larger paychecks now but a potential tax bill at filing time, a tradeoff worth thinking through deliberately rather than leaving to a default setting.

When to consult a tax professional

Consult a tax professional for a nonresident alien unsure how the special W-4 instructions apply to their specific situation, since getting this form wrong can lead to either an unexpected tax bill or unnecessarily reduced paychecks throughout the year. It’s also worth guidance after a major life change, a new job, marriage, or a new dependent, when unsure how to adjust a specific withholding amount to reflect the change accurately.

Using the IRS Tax Withholding Estimator

The IRS provides a free online Tax Withholding Estimator specifically designed to help fill out Form W-4 more accurately, particularly useful when a situation involves more than one job, self-employment income, or another factor that makes the standard worksheets feel confusing. According to this Remitly guide on immigrant tax obligations⁠(opens in new window), immigrants of every status generally have tax obligations that vary based on how their business or employment is structured, which is part of why getting withholding right from the start matters.

Why a new job always requires a fresh W-4

Even after filling out a W-4 accurately at a previous job, starting a new position always requires a new form specific to that employer, since withholding is calculated independently for each employer relationship rather than automatically transferring from a prior job.

Why claiming too many dependents can create a problem later

Overestimating the credits or adjustments claimed on a W-4 can result in too little tax being withheld throughout the year, leading to an unexpected tax bill, and possibly a penalty, at filing time, making accuracy on this form worth prioritizing over simply maximizing take-home pay in the short term.

Why a second job often needs special attention on your W-4

Working two jobs simultaneously, or being married with a working spouse, requires specific attention on a W-4’s multiple jobs worksheet, since failing to account for combined household income across both jobs is one of the most common reasons people end up significantly under-withheld.

Why a W-4 review after tax filing season makes sense

Right after filing a prior year’s return is often the best time to review whether withholding was accurate, since a clear, recent picture of whether money was owed or a large refund received informs exactly how to adjust a W-4 going forward.

Common questions about Form W-4

What happens if I don’t submit a Form W-4 at all?

An employer is required to withhold tax as if filing single with no additional adjustments, which is typically the highest default withholding rate, generally resulting in a smaller paycheck than might otherwise apply.
How often should I update my Form W-4?

The IRS recommends reviewing a W-4 whenever a personal or financial situation changes, a new job, a change in marital status, a new dependent, or a significant shift in other income, since withholding should reflect current, not past, circumstances.
Can I claim exemption from withholding on my W-4?

Only when meeting specific conditions, generally having had no federal income tax liability in the prior year and expecting none in the current year. This exemption must be renewed each year by a specific deadline, and it’s not automatically continued from year to year.

In Summary

Form W-4 is a routine but genuinely important piece of paperwork, since getting it right directly shapes both paycheck size throughout the year and eventual tax outcome. Find out more about W4 and W2 forms key differences.⁠(opens in new window)

This publication is provided for general information purposes only and is not intended to cover all aspects of the topics discussed herein. This publication is not a substitute for seeking advice from an applicable specialist or professional. The content in this publication does not constitute legal, tax, or other professional advice from Remitly or any of its affiliates and should not be relied upon as such. While we strive to keep our posts up to date and accurate, we cannot represent, warrant, or otherwise guarantee that the content is accurate, complete, or up to date.