Arizona Form A-4: Withholding Percentage Election and Filing Steps

Arizona Form A-4 is the state withholding election you give your employer to set how much Arizona income tax comes out of each paycheck. You pick one of seven percentages of your gross taxable wages, sign the form, and turn it in within five days of starting a job. Skip it, and your employer withholds at the default 2.0% rate until you file one.¹

How To Pick a Withholding Percentage

The form offers seven choices: 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, or 3.5% of your gross taxable wages.² Arizona’s flat income tax rate is 2.5%, so 2.5% withheld looks like a natural match. In practice the percentage applies to gross wages before the standard deduction and any credits, which means 2.5% usually overpays your actual liability by a comfortable margin.

For a single filer with one job and no unusual deductions, 2.0% often lands close to what you owe. If you file jointly, claim dependents, or qualify for credits such as Arizona’s family tax credit or school tax credits, 1.5% or even 1.0% may be enough. If you have income that isn’t subject to withholding — rental income, freelance work, investment gains — going up to 3.0% or 3.5% helps you avoid a lump sum in April.

The form also has a line for an extra flat dollar amount to be withheld from each paycheck on top of your chosen percentage.² It’s useful when the standard percentages don’t quite cover your situation, for example when you hold two jobs and want the second employer to withhold a bit extra to make up for the combined income.

Filling Out the Form Step by Step

Download the current form from the Arizona Department of Revenue’s withholding forms page.³ Many employers hand out a copy during onboarding. The form fits on a single page and takes a few minutes.

Personal information. Enter your full legal name, Social Security number, and current home address. The SSN connects your withheld taxes to the right account, and the address determines where your W-2 is mailed.
Line 1, withholding percentage. Check one box from the seven percentage options. You can only choose one.
Extra withholding. If you want an additional flat dollar amount taken from every paycheck, check the box and write the amount on the line. Leave it blank if the percentage alone is enough.
Signature and date. Your signature certifies that everything on the form is true under penalty of perjury.²

One common mistake: filling out a federal W-4 and assuming it covers state withholding too. It doesn’t. The W-4 handles the IRS side of your payroll. The A-4 is a separate election for Arizona taxes, and you need both.

Electing Zero Withholding

If you expect to owe no Arizona income tax for the year, you can elect a withholding percentage of zero.² “No Arizona income tax liability” means your gross tax comes to zero after subtracting credits such as the family tax credit, school tax credits, or credits for taxes paid to other states. A low income alone isn’t automatically enough. You need to account for the credits too.

Two conditions come with a zero election. If your situation changes mid-year and you realize you will owe tax, file a new A-4 right away and pick one of the standard percentages. The zero election also expires at the end of each calendar year. To keep it going, give your employer an updated A-4 before the new year starts, otherwise your employer can resume withholding at the 2.0% default until you turn in a fresh form.²

Part-time or seasonal agricultural workers whose main duties involve operating mechanically driven equipment cannot claim the zero election regardless of their expected tax liability. They must pick one of the seven standard percentages.

Where To Submit the Form and How To Change It

Give the completed A-4 to your employer’s payroll or human resources department, not to the Arizona Department of Revenue.² The state does not accept individual withholding elections directly. Your employer keeps the form on file and uses it to calculate your Arizona withholding going forward.¹

Most payroll systems apply a new election within one or two pay cycles. Check your next couple of pay stubs to confirm the change. If the old rate is still showing after a full month, follow up with payroll.

You can update your withholding at any time by completing a new Form A-4 and giving it to your employer.¹ There’s no limit on how often. Common reasons to revisit your election include getting married, having a child, starting a second job, or receiving a large raise. Life events that affect your federal W-4 almost always warrant a look at your state A-4 as well.

When A-4 Is Not the Right Form

Arizona withholding applies to wages for services performed inside the state, regardless of where you live.⁴ If you’re a non-resident who occasionally works in Arizona, withholding becomes mandatory once you’ve been physically present in the state for 60 days during the calendar year. Before that 60-day mark, you and your employer can agree to start withholding voluntarily, but it isn’t required.¹ The reverse also holds: if you live in another state and work entirely outside Arizona for an Arizona-based company, your employer is not required to withhold Arizona income tax at all.

Arizona Residents Working Outside the State

If you’re an Arizona resident employed by a company based in another state and you perform all your work outside Arizona, Form A-4 doesn’t apply. You can ask your employer to voluntarily withhold Arizona tax by filing Form A-4V, the Voluntary Withholding Request for Arizona Residents Employed Outside of Arizona.⁵ Your employer isn’t legally required to honor the request, but if they agree, the same withholding rules apply as if it were mandatory.

Military Spouses

Under the federal Military Spouses Residency Relief Act, wages earned in Arizona by a qualifying military spouse are exempt from Arizona withholding. You qualify if your spouse is an active-duty service member stationed in Arizona under military orders, you’re in Arizona solely to be with them, and you both maintain legal residence in another state.⁶

To claim the exemption, file Form WEC (Employee Withholding Exemption Certificate) with your employer instead of Form A-4. Attach a copy of your spouse’s most recent Leave and Earnings Statement and let your employer copy your military spouse ID.⁷ Renew the exemption by filing a new Form WEC at the start of each calendar year with fresh documentation. If your qualifying status ends through divorce, your spouse leaving the service, or you establishing Arizona as your permanent home, file a new Form WEC to close out the exemption and submit a standard Form A-4 to start Arizona withholding.

What Happens if You Withhold Too Little

If your withholding and any estimated payments fall short of what you owe, you’ll pay the balance when you file your Arizona return. That by itself isn’t a penalty. You simply write a check. But if the shortfall is large enough, the Department of Revenue may also assess an underpayment of estimated tax penalty.⁸ The penalty applies when your Arizona gross income exceeds certain thresholds and you haven’t made estimated payments to cover the gap. The specific penalty amount is calculated on Arizona Form 221.

If you know your withholding percentage isn’t going to cover other income sources, bump up your A-4 percentage, add an extra dollar amount on the form, or make quarterly estimated payments directly to the Department of Revenue. Estimated payments for tax year 2026 are due April 15, June 16, and September 15 of 2026, plus January 15, 2027.⁸

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Arizona Department of Revenue. Withholding Tax
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Arizona Department of Revenue. Arizona Form A-4 – Employee’s Arizona Withholding Election
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Arizona Department of Revenue. Arizona Withholding Percentage Election
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Arizona Legislature. Arizona Code 43-401 – Withholding Tax; Rates; Election by Employee
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Arizona Department of Revenue. Voluntary Withholding Request for Arizona Resident Employed Outside Arizona
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Arizona Department of Revenue. Arizona Form WEC – Employee Withholding Exemption Certificate
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Arizona Department of Revenue. Spouses of Active Duty Military Members
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Arizona Department of Revenue. Filing Notices of Penalties and Interest