You can get an Arizona tax extension that pushes your filing deadline from April 15 to October 15, a full six months of extra time to put the return together. Arizona grants it automatically if you’ve already filed a federal extension, made an electronic extension payment, or submitted Arizona Form 204 by the original due date. The catch is that the extension only buys time to file. You still have to pay at least 90% of what you owe by April 15, or a separate penalty kicks in.
Three Ways to Get the Extension
The easiest path is one you may have already taken. If you filed IRS Form 4868 for a federal extension, Arizona accepts it as your state extension too, with no separate paperwork required.1Arizona Department of Revenue. Making Payments, Late Payments, and Filing Extensions One small step you cannot skip: when you eventually file your Arizona return, check the “Filing Under Extension” box (box 82F) on the return itself. Miss that box and the state may treat the return as late even though your federal extension was valid.
The second path is paying electronically. An extension payment made through AZTaxes.gov by April 15 counts as your extension request on its own, so you can skip Form 204 entirely.1Arizona Department of Revenue. Making Payments, Late Payments, and Filing Extensions Use the “Make an Individual/Small Business Income Payment” link, and save the confirmation number as proof.
The third path is Arizona Form 204 itself, which you need only if you didn’t file a federal extension and aren’t paying electronically. The Department of Revenue grants the automatic six-month extension under A.R.S. ยง 42-1107 when the form is properly completed and at least 90% of the tax is paid by the original due date.2Arizona Legislature. Arizona Code 42-1107 – Extension of Time for Filing Returns Form 204 covers extensions for Forms 140, 140A, 140EZ, 140ET, 140PTC, 140PY, and 140NR.3Arizona Department of Revenue. Application for Filing Extension Form If you’re mailing a paper form, send it with a check for your estimated balance due to the Arizona Department of Revenue, P.O. Box 29085, Phoenix, AZ 85038-9085, and mail early enough to arrive by April 15 or use the postmark as proof.4Arizona Department of Revenue. Mailing Addresses
The 90% Payment Rule
This is where most extension problems begin. An extension gives you more time to file, not more time to pay. Arizona doesn’t demand that you pay 100% of your tax by April 15, but it does demand 90%. Pay at least that much of your eventual tax liability by the original due date and you avoid the extension underpayment penalty.5Arizona Department of Revenue. Arizona Form 204 Filing Extension for Individuals – Instructions
Fall short of 90%, and Arizona charges 0.5% of the unpaid tax for each 30-day period (or fraction of one) from the original due date until you pay, up to a maximum of 25% of the unpaid balance.5Arizona Department of Revenue. Arizona Form 204 Filing Extension for Individuals – Instructions Interest also starts running the day after April 15 on anything unpaid, calculated using the federal short-term rate plus three percentage points.6Arizona Department of Revenue. Interest Rates
Estimating is easier than it used to be. Arizona now applies a flat 2.5% individual income tax rate across all income levels and filing statuses.7Arizona Department of Revenue. Individual Income Tax Highlights When in doubt, overpay. Anything extra comes back as a refund when you file.
Deadlines for the 2025 Tax Year
For returns covering tax year 2025 and filed in 2026, two dates matter:
- April 15, 2026: original due date for your Arizona individual income tax return, the deadline to file Form 204 or make an electronic extension payment, and the deadline to pay at least 90% of your tax.
- October 15, 2026: extended due date for filing your return if a valid extension is on file.1Arizona Department of Revenue. Making Payments, Late Payments, and Filing Extensions
What Happens If You Miss the Extended Deadline
Arizona treats late filing more harshly than late payment. Miss October 15 without filing, and the late-filing penalty is 4.5% of the unpaid tax for each month or partial month until you file, capped at 25% of the tax due.8Arizona Legislature. Arizona Code 42-1125 – Civil Penalties Definition
The separate late-payment penalty is 0.5% of the unpaid tax per month, capped at 10%. When both penalties apply to the same period, the combined total cannot exceed 25%.8Arizona Legislature. Arizona Code 42-1125 – Civil Penalties Definition Interest keeps running daily on any unpaid balance from the original due date until paid in full.9Arizona Department of Revenue. Filing Notices of Penalties and Interest Either penalty can be waived if you can show reasonable cause with documentation and the failure wasn’t due to willful neglect, but that’s a high bar.
Military and Overseas Filers
Arizona doesn’t tax active duty military pay, so service members whose only Arizona-source income is military pay generally don’t need to file a state return at all.10Arizona Department of Revenue. Military Tax Filing For military members and civilians living abroad who do have Arizona filing obligations, the IRS grants an automatic two-month extension to June 15, and Form 4868 can extend that further.11Internal Revenue Service. Application for Automatic Extension of Time to File U.S. Individual Income Tax Return Because Arizona honors valid federal extensions automatically, those federal dates flow through to the state return. Combat zone extensions follow the federal timeline too; IRS Publication 3 (Armed Forces’ Tax Guide) covers the specifics.12Internal Revenue Service. Filing Extensions and Tax Return Preparation Assistance for Military Personnel Stationed Abroad or in a Combat Zone