What Is Arizona A-4 Withholding and How Does It Work

Arizona Form A-4 is the state tax withholding election you give your employer to set how much Arizona income tax comes out of each paycheck. Instead of estimating allowances the way the federal W-4 does, Arizona A-4 withholding is a simple percentage pick: you choose one of seven flat rates between 0.5% and 3.5% of your gross taxable wages, and that rate applies to every check until you file a new form.¹ With Arizona now using a flat 2.5% income tax rate, picking a percentage close to 2.5% is what keeps most people from owing or overpaying at tax time.²

What the A-4 Does

Every Arizona employer is required to withhold state income tax from employee wages.³ The A-4 is how you tell them the rate. For withholding purposes, “gross taxable wages” generally means the amount that will land in Box 1 of your federal W-2.¹ Your employer multiplies that figure by your chosen percentage each pay period and sends the money to the Arizona Department of Revenue on your behalf.

The federal W-4 asks about dependents, deductions, and credits. The A-4 doesn’t. You pick one number and sign.

Picking Your Percentage

Your seven options are 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, and 3.5% of gross taxable wages.¹ Because Arizona’s income tax is a flat 2.5% regardless of income level or filing status, the math is more direct than it used to be.²

For most employees with one job and no significant outside income, choosing 2.5% should land you close to even at tax time. If you have a side business, investment income, or a working spouse pushing your household into a bigger total liability, 3.0% or 3.5% builds in a cushion. Picking 0.5% or 1.0% will almost certainly leave you owing money in April unless your deductions or credits bring your effective rate well below the flat rate.

Adding a Flat Dollar Amount

The form also lets you request an extra dollar amount withheld from each paycheck on top of the percentage.¹ This is useful when your tax picture is more complex than one W-2. Rental income, freelance work, or a planned retirement distribution can all be covered through payroll instead of quarterly estimated payments.

Electing Zero Withholding

You can elect 0% withholding only if two things are true: you had no Arizona tax liability last year, and you don’t expect any this year.⁴ This election has to be renewed every year. It mostly applies to workers whose income is below the filing threshold or who are fully offset by credits.

Filing the Form

Filling out the A-4 takes about two minutes. You write in your full legal name, Social Security number, and address, check the box for your percentage, add any extra dollar amount, then sign and date it. The current version is available from the Arizona Department of Revenue.⁵

Give the completed form to your employer’s payroll or HR department. Don’t mail it to the Department of Revenue. The filing obligation sits with the employer, who keeps a copy, gives you one, and files one with the state.³ Many employers now accept it through a digital payroll portal.

Changes take effect on the next regular payroll cycle once the form is processed; you can’t future-date them.⁶ Check your next pay stub to confirm the new percentage is actually being applied.

New Hire Deadline and the Default Rate

If you’re starting a new job, you have five days to turn in a completed A-4.³ Employers must notify you about the election and keep blank forms available.

Miss the deadline and your employer is required to withhold at the default rate of 2.0% until you submit a form.⁷ That’s a half point under the 2.5% flat tax, which means the default quietly under-withholds you and will likely leave a balance due in April. Submitting the form on time avoids both the underpayment and the catch-up later.

If You Live Out of State

If you live outside Arizona but occasionally work in the state, your employer isn’t required to begin Arizona withholding until you’ve been physically present and working here for 60 days in a calendar year.⁸ Days in transit, personal days, and training or meetings not tied to your employer’s Arizona operations don’t count toward that 60. You and your employer can agree to begin withholding earlier if you’d rather not deal with an estimated payment later.

When to File a New A-4

You can submit a new A-4 any time, as often as you want. The usual reasons to revisit it:

You owed a sizable balance or received a sizable refund last year. Either one means your percentage was off: owing points to going higher, a refund of more than a few hundred dollars points to going lower.
Your household income shifted. A spouse starting or stopping work, a new side income, or a large investment gain all change what you owe.
You elected 0% last year. That election expires annually and must be resubmitted if you still qualify.

With the flat 2.5% rate, a single-job employee with no outside income usually gets very close to zero owed or refunded by selecting 2.5%.² The complication comes with multiple income sources, large itemized deductions, or credits that push your effective rate below the flat rate; those are the situations where the extra dollar line or a higher percentage earns its keep.

1
Arizona Department of Revenue. Arizona Form A-4 Employee Arizona Withholding Election
2
Arizona Department of Revenue. Individual Income Tax Highlights
3
Arizona Legislature. Arizona Revised Statutes Title 43 – 401 Withholding Tax Rates Election by Employee
4
Arizona Department of Human Resources. New Arizona Income Tax Withholding Rates Effective for Wages Paid After December 31, 2022
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Arizona Department of Revenue. Arizona Withholding Percentage Election
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ADOA General Accounting Office. Agency Payroll Guide Taxes
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Arizona Department of Revenue. Withholding Tax – Individual
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Arizona Department of Revenue. Arizona Withholding Tax