120/165EXT: 165EXT Application for Automatic Extension of Time to File Corporation, Partnership, and Exempt Organization Returns (2025)

Who files this form

Arizona Form 120/165EXT is used to request an automatic extension of time to file corporation, partnership, and exempt organization returns. The listed return types are Forms 120, 120A, 99T, 99M, 120S, and 165.

Arizona also accepts a valid federal extension for the same period covered by the Arizona extension.

S corporations and partnerships requesting an extension for a composite Form 140NR return for nonresident individual shareholders or partners must use Form 204 instead.

When it's due

For tax year 2025, the extension application must be postmarked on or before the return’s original due date. If that date falls on a Saturday, Sunday, or legal holiday, the application must be postmarked by the following business day.

The form does not print specific calendar due dates. It provides these extension periods:

• Forms 120, 120A, 99T, and 99M: seven months.
• Forms 120S and 165: six months.

At least 90% of the tax liability shown on the return must be paid by the original due date to avoid the extension underpayment penalty. Interest accrues on additional tax due from the original due date until paid.

What you'll need

Have the following information ready to complete the form:

• Business name, EIN, mailing address, and business telephone number.
• Calendar-year or fiscal-year information, including whether a fiscal-year return uses a 52/53-week taxable year.
• The type of return being extended and whether you will use a federal extension.
• Whether this is the first return under the name and EIN, whether the name or address changed, and any prior EIN if the EIN changed.
• Tax liability, estimated tax payments, and any extension payment made electronically or enclosed with the application.
• The signing officer’s or agent’s signature, date, title, printed name, and business phone number. The form also has a field for the agent’s TIN.

How to file

Complete the taxpayer information, select the return type, and check the applicable extension box. Enter the requested extension date and taxable year ending where applicable.

For the extension payment computation, enter tax liability on line 1 and estimated tax payments on line 2. Subtract line 2 from line 1 for line 3. Enter electronic extension payments on line 4 and any enclosed payment on line 5. Have the officer or agent sign the declaration.

With payment, mail the application and payment to:

Arizona Department of Revenue

PO Box 29085

Phoenix, AZ 85038-9085

Without payment, mail the application to:

Arizona Department of Revenue

PO Box 29079

Phoenix, AZ 85038-9079

Make checks payable to Arizona Department of Revenue and include the EIN on the payment.

Taxpayers with a tax liability of $500 or more for tax year 2025 must make tax payments by electronic funds transfer.

Common mistakes

• Using this form for a composite Form 140NR extension. S corporations and partnerships must use Form 204 for that purpose.
• Missing the postmark deadline. Applications must be postmarked by the original due date, with the stated weekend and legal-holiday exception.
• Paying too little by the original due date. Paying less than 90% of the tax liability shown on the return triggers the extension underpayment penalty. Interest also accrues on additional tax due until paid.
• Overlooking mandatory electronic payment. For tax year 2025, taxpayers with tax liability of $500 or more must pay by electronic funds transfer.
• Leaving the EIN off a payment. The form directs taxpayers to include it.
• Writing in the revenue-use-only area. The form says not to mark that area.

Questions people ask

Will Arizona accept my federal extension?

Arizona accepts a valid federal extension for the same period covered by the Arizona extension. The form includes a checkbox for using a federal extension.

How long is the automatic extension?

The form provides a seven-month extension for Forms 120, 120A, 99T, and 99M, and a six-month extension for Forms 120S and 165.

Can I owe penalties or interest while I have an extension?

Yes. The extension underpayment penalty applies if at least 90% of the tax liability shown on the return has not been paid by the original due date. Interest accrues on additional tax due from that date until paid. Taxpayers subject to the extension underpayment penalty are not also subject to the late payment penalty specified in A.R.S. § 42-1125(D).

Can a partnership use the payment computation?

The form lists Form 165 partnerships that elected to pay tax at the entity level among those using the extension payment computation.

Official sources

• https://azdor.gov/forms