Arizona Form A-4 is the Employee’s Arizona Withholding Election that every employee working in Arizona uses to tell their employer what percentage of state income tax to take out of each paycheck. You hand the finished form to your employer, not to the state, and your choice controls how much Arizona tax leaves your pay until you file a new one.
Getting this small form right matters more than most people think. Pick a rate that is too low and you could owe a surprise bill plus interest when you file your Arizona return; pick one that is too high and you hand the state an interest-free loan all year. Arizona moved to a flat 2.5% income tax in 2023, and the A-4 now offers seven simple percentage choices instead of the old “percentage of federal tax” method, which means the Arizona Department of Revenue processes withholding for millions of W-2 workers through this single page each year.
Here is what you will learn in this guide:
- 📝 How to fill out every box on the current 2026 Form A-4 (ADOR 10121, rev. 25) line by line.
- 💵 How to pick the right withholding percentage so you do not owe or overpay at tax time.
- 🚫 How the zero-withholding election works and the strict two-part test you must pass to use it.
- 👥 Three full walkthroughs using real-life filers, from a brand-new hire to a retiree.
- ⚠️ The most common A-4 mistakes that trigger surprise tax bills and how to dodge them.
What the Form Is and Who Must File It
Form A-4 is the document Arizona uses to set your state income tax withholding rate. The form is required under Arizona Revised Statutes § 43-401, which orders your employer to withhold Arizona income tax from pay you earn for work done in Arizona. You complete the A-4, and your employer applies the rate you choose to your gross taxable wages each pay period.
Almost every employee who performs services in Arizona must deal with this form. That includes new hires, current workers who want to change their rate, and certain nonresidents who choose to have Arizona tax taken out. The form does not go to the Department of Revenue; you give it to your employer, who keeps it on file and uses it to run payroll.
The current version is the 2026 Form A-4, printed as ADOR 10121 (25) in the bottom corner. This version dropped the old “percentage of federal tax withheld” choices and replaced them with seven flat rates applied directly to your Arizona gross taxable wages. Always check the revision code in the corner so you know you are using the right year’s form, because employers will reject an outdated version.
If you never turn in an A-4, your employer must withhold at the default rate of 2.0% of your gross taxable wages. That default protects the state, but it may not match your real tax picture. A high earner might under-withhold at 2.0%, while a low earner might give up cash they did not owe, so filing the form puts you in control instead of the default.
Before You Start: Documents and Information You Need
Filling out the A-4 takes only a few minutes once you have your details in front of you. Gathering this short list first keeps you from guessing, and a wrong guess on this form follows you through every paycheck for the rest of the year.
- Your full legal name as it appears on your Social Security card, because your employer matches it to payroll and tax records, and a mismatch can delay or misfile your withholding.
- Your Social Security number (SSN), since the state ties your withholding to this number; a wrong SSN sends your tax payments to the wrong account.
- Your current home address, including city, state, and ZIP code, because the state and your employer use it for your year-end W-2 and any notices.
- Your expected annual Arizona wages, which help you judge whether a low rate will leave you owing money in April.
- Last year’s Arizona tax return, so you can see if you owed tax or got a refund and pick a rate that fits.
- Your filing status and rough deductions, because someone who itemizes or has credits may safely choose a lower rate than someone who does not.
- Any other income (a side job, investments, or a spouse’s pay), since that extra money can push you into owing if you withhold too little from your main job.
- Your prior-year Arizona tax liability, which you must confirm was zero before you can even consider the zero-withholding election.
Having these items ready also helps you decide whether to add an extra flat-dollar amount on the form. If you owed money last year, that history is your best clue that the base percentage alone may not be enough.
Where to Get the Form and How to Access It
Most workers never have to hunt for the A-4 because the employer hands it over during onboarding, often inside a hiring packet or a digital payroll system. If you need a fresh copy, download the official one directly from the Arizona Form A-4 page on the Department of Revenue website. Pulling it from the official source guarantees you get the current ADOR 10121 (25) version and not an expired form a search engine dug up.
You can also use the state’s withholding tools and calculator to estimate the right percentage before you check a box. The calculator asks about your wages and tax situation, then suggests a rate, which takes the guesswork out of the choice.
Many large employers, including the State of Arizona, deliver the A-4 through an online HR portal where you check your boxes and e-sign on screen. If your employer uses a portal, follow their on-screen steps; the fields are the same as the paper form. Whichever path you use, the form itself is free, and you should never pay a third-party site to access it.
Keep a copy of whatever you submit. Whether you fill out paper or click through a portal, save a PDF or photo for your own records so you can prove what rate you chose if a paycheck looks wrong later.
Step-by-Step: How to Fill Out Form A-4 Line by Line
The A-4 fits on one page and splits into two parts: a short block of personal information at the top and the withholding election choices below. Work through each field in order, and do not skip the signature, because an unsigned form is not valid and forces your employer back to the default rate.
Field 1: Type or Print Your Full Name
This top box asks for your complete legal name, first and last. Write it exactly as it appears on your Social Security card, in clear print or type, with no nicknames. For example, Maria Elena Lopez prints her name in full rather than writing Mari Lopez.
If you recently married or changed your name, use the name that currently matches Social Security Administration records, not the one you plan to switch to later. The most common mistake here is using a nickname or a new married name that has not been updated with the SSA, which can cause a name-to-SSN mismatch and delay how your withholding posts. Many people think this name only needs to match their driver’s license, but the agency cross-checks it against SSA and tax records, so the card is what counts.
Field 2: Your Social Security Number
This field asks for your nine-digit Social Security number. Write it in the standard format, such as 123-45-6789, and double-check every digit before moving on. For example, David Nguyen enters 601-23-4567 and reads it back once to confirm.
If you have an Individual Taxpayer Identification Number (ITIN) instead of an SSN because you are a nonresident, enter that number here. The biggest error on this line is a single transposed digit, which sends your tax payments to the wrong account and can leave your real account looking unpaid. Some filers believe a small typo will get caught and fixed automatically, but the state matches payments by this exact number, so even one wrong digit can cause months of cleanup.
Field 3: Home Address (Number and Street or Rural Route)
This line asks for your street address where you live. Enter your house or apartment number and street name, such as 4820 N Central Ave, Apt 3B. Spell out the street clearly so mail reaches you.
If you get mail at a P.O. Box but live somewhere else, you may list the P.O. Box, though a physical address is better for payroll records. The common slip here is leaving an old address from a prior job, which means your year-end W-2 and any state notices go to the wrong place. People often assume their employer already knows their current address from another form, but the A-4 stands on its own, so fill it in fresh.
Field 4: City or Town, State, and ZIP Code
This box completes your mailing address with the city, the state, and your five-digit ZIP code. For example, Maria Elena Lopez writes Phoenix, AZ 85012. Keep it on one line as the form is laid out.
If you just moved to Arizona, use your new Arizona address even if your job started before the move. The frequent mistake is a wrong or missing ZIP code, which can misroute your W-2 at year end. Some filers think the state field is optional because they work in Arizona, but you must still write AZ (or your actual home state if you are a nonresident) so the record is complete.
Field 5: Withholding Percentage Election (Choose Only One Box)
This is the heart of the form. You pick one flat percentage that your employer will apply to your gross taxable wages every pay period. The 2026 form offers seven choices: 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, or 3.5%. Check a single box only; checking two or none makes the election invalid.
To choose well, think about your total tax picture. Arizona’s flat income tax rate is 2.5%, so many single-job workers with standard deductions land near the 2.0% box and come out close to even. For example, David Nguyen, a single filer earning $60,000 with no side income, checks 2.0% and expects a small refund or a small balance. If you owed money last year, bump up to 2.5% or 3.0%; if you got a large refund, drop to 1.5% or lower to keep more of each paycheck.
The most damaging mistake here is choosing a rate far below your real tax rate to inflate your take-home pay, which leaves you facing a lump-sum bill plus possible underpayment interest when you file your Arizona individual return. A common misconception is that 2.5% will always be exactly right because the state tax is 2.5%; in truth, your standard deduction and credits often lower your effective rate, so a slightly lower box can still cover your bill. Remember the rate applies to gross taxable wages, not to your federal tax, which is the opposite of how the old version worked.
Field 6: Additional Amount to Be Withheld Each Pay Period
This optional line lets you add a flat dollar amount on top of the percentage you chose. Write a whole-dollar figure, such as $25.00, and your employer takes that extra amount out of each paycheck. Leave it blank if you do not want extra withholding.
This line is a safety valve for people with other income that has no Arizona tax taken out. For example, Janet Reyes, who earns rental income on the side, checks 2.0% and writes $40 on this line so her job covers the tax on her rental too. The common error is treating this as a percentage and writing 3 when you mean three percent, which actually adds only three dollars; this field is dollars, not a rate. Many filers skip this line because they do not know it exists, then wonder why a side gig leaves them owing, so use it when your main paycheck is not your only income.
Field 7: Zero Withholding Election (Box 3)
This box lets you elect zero Arizona withholding, but only if you pass a strict two-part test. By checking it, you certify that you had no Arizona income tax liability for the prior year and that you expect no Arizona income tax liability for the current year. Both must be true; meeting only one does not qualify you.
For example, Robert and Linda Hayes, retirees whose only income is Social Security and a small pension that produced no Arizona tax last year and none expected this year, check Box 3 to stop withholding. The serious mistake here is checking this box just to boost take-home pay when you do, in fact, owe Arizona tax, which leaves you with the full bill plus interest at filing and no money set aside. A widespread misconception is that the zero election is permanent; it is not, and if your situation changes mid-year you must file a new A-4 right away with a real percentage. Note that “no tax liability” means your gross tax minus credits, such as the family tax credit or credits for taxes paid to other states, came out to zero.
Field 8: Signature
This line makes the whole form legal. Sign your name in ink (or e-sign in a portal) to certify that the election you marked above is your choice. For example, Maria Elena Lopez signs Maria Elena Lopez on the signature line.
An electronic signature inside your employer’s payroll portal counts the same as a pen signature. The number-one failure on the A-4 is forgetting to sign, which makes the form invalid and forces your employer to withhold at the default 2.0% as if you filed nothing. Some people think typing their name in the name box at the top doubles as a signature; it does not, so you must complete the separate signature line for the form to take effect.
Field 9: Date
Next to your signature, write the date you signed the form. Use a clear format such as 01/15/2026. This date tells your employer when your election starts.
If you are a new hire, sign and date within your first five days of work so the right rate applies from your first paycheck. The common mistake is leaving the date blank or backdating it, which can muddy when the new rate should begin. People sometimes assume the date does not matter, but your employer uses it to know which pay period your election kicks in, so always fill it in honestly with the day you sign.
Three Filled-Out Examples Using Real Scenarios
Seeing the form completed end to end makes the choices concrete. Below are three common filers, each walked through the A-4 from the name box to the date.
Scenario 1: David Nguyen, a new hire choosing the standard rate. David is single, earns $60,000 at one job, takes the standard deduction, and has no other income. He wants to come out close to even at tax time.
| Form Section | What David Enters |
|---|---|
| Full name | David Nguyen |
| Social Security number | 601-23-4567 |
| Home address | 155 W Roosevelt St, Apt 9 |
| City, state, ZIP | Phoenix, AZ 85003 |
| Withholding percentage (Field 5) | Checks the 2.0% box |
| Additional amount (Field 6) | Leaves blank |
| Zero election (Box 3) | Leaves blank |
| Signature | David Nguyen |
| Date | 01/10/2026 |
Scenario 2: Janet Reyes, a current employee lowering her rate and adding extra. Janet got a big refund last year, so she wants more take-home pay, but she also earns rental income with no tax withheld and does not want to owe on it.
| Form Section | What Janet Enters |
|---|---|
| Full name | Janet Marie Reyes |
| Social Security number | 540-88-1290 |
| Home address | 2210 E Camelback Rd |
| City, state, ZIP | Phoenix, AZ 85016 |
| Withholding percentage (Field 5) | Checks the 1.5% box |
| Additional amount (Field 6) | Writes $40 |
| Zero election (Box 3) | Leaves blank |
| Signature | Janet Marie Reyes |
| Date | 03/02/2026 |
Scenario 3: Robert and Linda Hayes, retirees electing zero withholding. Robert took a part-time job, but the couple’s only taxable income produced zero Arizona tax last year and is expected to again this year, so he qualifies for the zero election.
| Form Section | What Robert Enters |
|---|---|
| Full name | Robert James Hayes |
| Social Security number | 333-22-7654 |
| Home address | 7845 E Lincoln Dr |
| City, state, ZIP | Scottsdale, AZ 85250 |
| Withholding percentage (Field 5) | Leaves blank |
| Additional amount (Field 6) | Leaves blank |
| Zero election (Box 3) | Checks the box and certifies both conditions |
| Signature | Robert James Hayes |
| Date | 01/20/2026 |
How to File the Completed Form
You do not mail Form A-4 to the Arizona Department of Revenue. You give the finished form to your employer, who keeps it on file and uses it to set your payroll withholding. There is no filing fee for the A-4 at any channel.
- In person or on paper: Hand the signed paper form to your HR or payroll department. Ask for confirmation that they received it, and keep your own copy. The change usually shows up within one or two pay periods.
- Through an employer portal: Many companies, including the State of Arizona HR system, let you complete and e-sign the A-4 online. Submit it in the portal, then save or screenshot the confirmation screen as your proof.
- By email or upload: Some employers accept a scanned, signed copy by secure email or document upload. Send it to the exact contact your payroll team gives you, and keep the sent message as proof.
Whichever channel you use, your proof of filing is your saved copy plus any confirmation from payroll. Federal law sends your federal withholding to the IRS through Form W-4, but the A-4 stays between you and your employer for state tax, so there is no government receipt to wait for. New hires should turn it in within the first five days of work so the correct rate applies right away.
What Happens After You File
Once your employer accepts the form, they apply your chosen percentage to your gross taxable wages starting with the next available pay period. By law, that adjustment should happen within one or two pay cycles, so check your next paystub to confirm the new state tax line looks right. If it does not change, follow up with payroll before more paychecks go out at the old rate.
Your election stays in place until you file a new A-4. There is no need to refill it every year for a standard percentage choice, which means a rate you set in 2026 keeps running into later years unless you change jobs or submit a replacement. The one exception is the zero-withholding election, which you should revisit each year to make sure you still pass both conditions.
At year end, your employer reports the Arizona tax they withheld on your W-2. You then use that figure on your Arizona income tax return to see whether you owe more or get a refund. If you withheld too little all year, this is when the shortfall, and any underpayment interest, comes due.
Mistakes to Avoid When Filling Out the Form
Small slips on this one-page form can cost you real money or a delay in your withholding. Watch for these specific errors.
- Forgetting to sign. An unsigned form is invalid, so your employer reverts you to the default 2.0% rate.
- Checking more than one percentage box. Two checked boxes void the election, and you fall back to the default rate.
- Picking a rate far too low. A rate below your real tax rate leaves you owing a lump sum plus possible interest at filing.
- Picking a rate too high. Over-withholding gives the state an interest-free loan and shrinks every paycheck for nothing.
- Wrong Social Security number. A transposed digit sends your tax payments to the wrong account and can look unpaid.
- Using a nickname or outdated name. A name that does not match SSA records can delay how your withholding posts.
- Treating Field 6 as a percentage. Writing 3 expecting three percent adds only three dollars and leaves you short.
- Checking the zero box without qualifying. If you actually owe tax, you face the full bill plus interest with nothing set aside.
- Assuming the zero election is permanent. It is not, and failing to update it after your income changes causes underpayment.
- Using an outdated form version. An old “percentage of federal tax” A-4 will be rejected, delaying your election.
- Leaving the date blank. A missing date muddies when your new rate should begin.
- Never filing at all. No form means automatic 2.0% withholding that may not fit your situation.
Do’s and Don’ts
A few simple habits keep your withholding accurate and your records clean.
Do’s
- Do check last year’s return first, because it tells you whether you owed or overpaid and points to the right rate.
- Do use the state withholding calculator, since it matches a percentage to your real wages and tax picture.
- Do file within five days of a new job, so the correct rate applies from your first paycheck.
- Do keep a copy of what you submit, because it is your only proof of the rate you chose.
- Do review your next paystub, to confirm the new state tax line took effect.
- Do update the form after big life changes, like a raise, marriage, or new side income, so your rate stays accurate.
Don’ts
- Don’t pick the lowest rate just for bigger paychecks, because the tax still comes due at filing.
- Don’t check the zero box to game your pay, since you must truly meet both conditions.
- Don’t leave the signature line blank, as it invalidates the entire form.
- Don’t guess your Social Security number, because one wrong digit misroutes your payments.
- Don’t use an old version of the form, since employers will reject it.
- Don’t forget side income, because your main paycheck may not cover the tax on it.
Filing on Your Own vs. Getting Help
Most workers fill out the A-4 alone in a few minutes, but some situations call for a tax pro. The table below weighs both paths.
| Filing on Your Own | Getting Professional Help |
|---|---|
| Free and fast, since the form is short and self-explanatory for a single job. | Adds cost, but a pro can model your exact tax picture across multiple income sources. |
| Full control to change your rate anytime by filing a new form. | Helpful when you have side income, investments, or a working spouse to balance. |
| Fine for standard single-job filers who take the standard deduction. | Worth it if you owed a large balance last year and want to avoid a repeat. |
| Risk of guessing wrong on the rate and owing at tax time. | Reduces the risk of underpayment interest by setting a precise rate and extra amount. |
| You must keep your own records and double-check your paystub. | A pro tracks your withholding alongside estimated payments and credits. |
| Pros: quick, free, flexible. Cons: easy to misjudge the right rate. | Pros: accuracy, peace of mind. Cons: costs money, may be overkill for simple cases. |
Frequently Asked Questions
Do I send Form A-4 to the Arizona Department of Revenue?
No. You give the completed form to your employer, who keeps it on file and uses it to set your payroll withholding. The state never receives the form directly.
What happens if I never fill out an A-4?
No form means your employer must withhold at the default rate of 2.0% of your gross taxable wages until you turn one in.
Is there a fee to file Form A-4?
No. The form is free through every channel, whether you submit paper to HR or e-sign it in an employer portal.
Can I change my withholding rate later?
Yes. File a new A-4 anytime, and your employer applies the new rate within one or two pay periods, replacing your old election.
Does the percentage apply to my federal tax or my wages?
No, not to your federal tax. On the current form, the rate applies to your Arizona gross taxable wages, unlike the old version that used federal tax.
In Field 5, can I check two percentage boxes?
No. You must check only one box; checking two voids the election and drops you to the default 2.0% rate.
In Field 6, do I write a percentage or a dollar amount?
No percentage goes here. Field 6 takes a flat dollar amount, so write $25.00, not a rate, for extra withholding each pay period.
Do I qualify for the zero-withholding election in Box 3?
No, unless you had zero Arizona tax liability last year and expect zero this year. You must meet both conditions to check it.
Does typing my name at the top count as my signature?
No. The name box and the signature line are separate, and you must complete the signature line for the form to be valid.
Do I have to refile the A-4 every year?
No for a standard percentage choice, which stays in effect until you change it. But you should revisit a zero election each year.
What rate should a typical single-job worker choose?
Yes, many land near 2.0% since Arizona’s flat tax is 2.5% and the standard deduction lowers the effective rate. Check your prior return to confirm.
Can a nonresident working in Arizona use Form A-4?
Yes. Certain nonresidents may file the A-4 to voluntarily elect Arizona withholding on the compensation they earn while working in Arizona.
What if my situation changes after I elect zero withholding?
Yes, you must act. File a new A-4 right away with a real percentage if you start to expect Arizona tax liability during the year.
Is an electronic signature in my employer’s portal valid?
Yes. An e-signature inside a payroll portal carries the same weight as a pen-and-ink signature on the paper form.
Related reading
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