Introduction
Filing federal Form 7004 does not mean every state has granted you more time. That assumption catches out Australian owners of U.S. C corporations every filing season, and the penalties arrive from state revenue departments, not the IRS.
This guide is for Australian businesses and other international owners of U.S. C corporations that file federal Form 1120. It separates the federal income-tax extension from state corporate tax extensions, which follow their own rules.
You'll find 2026 deadlines, extension forms, payment rules, state-by-state differences, penalties, foreign-ownership issues and a filing checklist. Dates and rules change, so confirm each against the current IRS and state revenue-department guidance before you file. Last reviewed: 2026.
Key Takeaways
- Form 7004 extends federal filing time; each state needs its own check.
- An extension gives more time to file, not more time to pay.
- States may levy franchise, gross receipts or other taxes even without a corporate income tax.
- Confirm nexus, apportionment and combined-return rules before relying on a federal extension.
2026 Form 1120 Extension Deadlines at a Glance
For a calendar-year 2025 return, the key federal dates are:
| Item | Date |
|---|---|
| Original Form 1120 due date | 15 April 2026 |
| Form 7004 filing deadline | 15 April 2026 |
| Federal extended due date | 15 October 2026 |
| State deadline | Varies by state (see below) |
The IRS Form 1120 instructions set the original deadline at the 15th day of the 4th month after year-end. If that day falls on a weekend or legal holiday, the deadline moves to the next business day.
Short-period and final returns follow the same 4th-month rule, counted from the end of the short period or the date of dissolution.
A June 30 year-end is a special case. For years beginning before 1 January 2026, the original due date is 15 September 2026 with a seven-month extension. For years beginning in 2026, the extension is six months.
Disaster relief can shift dates too. The IRS moved covered Hawaii deadlines to 8 July 2026, and Hawaii's state relief for eligible taxpayers ran to 20 August 2026.
Don't mix up entity types
Form 1120 is for C corporations. Form 1120-S, Form 1065 and personal returns have different due dates and extension rules. Applying an S corporation or partnership deadline to a C corporation is a common and costly error.
Do not assume your federal extension carries over. Some states accept it, some demand a separate form, and some attach conditions such as timely payment.
Verify every date against the current IRS Form 7004 instructions and the relevant state revenue-department page.
How Federal and State Extensions Work Together
What Form 7004 does
Form 7004 gives an eligible Form 1120 filer an automatic six-month extension to file. You submit one form per return by the original due date. The form asks for the EIN, return code, fiscal-year dates where relevant, and estimated tax information.
Most filers e-file. The IRS contacts you only if it rejects the request, so keep your electronic confirmation or proof of mailing. The tax itself stays due on the original date.
The four state scenarios
- Federal extension accepted automatically. Pennsylvania grants a state extension to taxpayers with a federal one. Oregon has no state form and uses Form 7004.
- Accepted with conditions. Georgia wants a copy of Form 7004 attached. Wisconsin gives 30 days after the federal extended date, but payment isn't extended.
- Separate state form required. Connecticut uses Form CT-1120-EXT. New York uses Form CT-5, filed by the original due date with properly estimated tax paid.
- No form needed. California grants an automatic seven-month filing extension, and Form 3539 is only a payment voucher.
Testing whether your state extension is valid
Confirm these points before you rely on a state extension:
- Tax type, return form and tax year
- Filing method and payment threshold
- Whether the company files alone or in a combined or consolidated group
Group rules often differ from single-member rules.
The payment rule
Estimated tax, the payment due with an extension, interest, and late-payment and late-filing penalties are separate items. Some states set a minimum payment to keep an extension valid:
- Arizona expects 90% of liability by the original due date
- New Hampshire’s automatic extension applies only if 100% of tax is paid by the due date
Always check the current-year rule.
Nexus for foreign-owned corporations
A U.S. subsidiary can owe state tax even when its federal liability is small. State filing duties depend on nexus: employees, property, sales and economic activity in the state. Apportionment then determines how much income each state taxes.
South Dakota v. Wayfair concerned sales-tax collection, not income-tax extensions. The Multistate Tax Commission's P.L. 86-272 statement covers limits on state net-income taxation for protected solicitation. Thresholds remain state-specific.
State-by-State Quick Reference for Form 1120 Filers
The groupings below come from official state sources. Several states publish rules only in older instructions, so confirm each on the state's current page. Form names, payment portals and filing addresses can change mid-season.
States that accept a valid federal extension
- Delaware: a six-month federal extension extends state filing; payment is due on the original date (2024 instructions).
- Georgia: attach the federal Form 7004 (2022 instructions).
- Oregon: no state form; use Form 7004 (2023 instructions).
- Pennsylvania: automatic state extension with a federal one.
- Wisconsin: 30 days past the federal extended date.
- Oklahoma: accepted if there is no Oklahoma liability (2025 instructions).
- North Dakota: one month after the federal extended date.
States requiring a separate extension
- Connecticut: Form CT-1120-EXT; payment is not extended.
- New York: Form CT-5 for six months, then up to two three-month requests on CT-5.1.
- Kentucky: Form 720EXT accompanies the payment.
- Missouri: Form MO-7004, up to 180 days.
- Tennessee: Form FAE-173.
- Vermont: Form BA-403; payment not extended.
- Michigan: Form 4, extending to the last day of the eighth month after the original due date, regardless of any federal extension.
- South Carolina: Form SC1120-T.
Automatic or payment-conditioned extensions
- California, Illinois, Minnesota, Virginia: automatic seven-month filing extensions.
- Maine: automatic six months.
- Maryland: automatic seven months if Form 500E is timely filed.
- New Jersey: six months; no extension to pay.
- New Hampshire: seven months, automatic only if 100% of tax is paid by the due date.
- Arizona: up to six months; 90% of liability due by the original date.
- North Carolina: seven months for tax years beginning on or after 1 January 2025.
- Texas: online request; payment of at least 90% of current report tax or 100% of prior report tax, subject to conditions.
Unusual dates and procedures
- Montana: the Department of Revenue lists a 15 November calendar-year extension deadline.
- Alaska: due the 15th day of the month after the federal due date.
- Kansas: one month after the federal deadline.
- Louisiana: six months, tied to a timely federal request.
- Hawaii: automatic extension under Form N-30 instructions; Form N-201V is not replaced by Form 7004.
For states not listed, such as Alabama, Colorado, Florida, Indiana, Iowa, Massachusetts, Nebraska, Ohio and Rhode Island, use the official pages for the current form, due date and extension terms.
States without a broad corporate income tax
- South Dakota: no corporate income tax.
- Washington: business and occupation tax on gross income.
- Nevada: Commerce Tax, with a separate 30-day good-cause extension to file and pay.
- Texas: franchise-tax and information reports.
- Ohio: Commercial Activity Tax.
- Delaware: annual reports and franchise or license taxes; due 1 March.
- Wyoming: annual reports and franchise or license taxes.
A return or extension may still be needed in these states. Confirm each one.
Factors that can change your deadline
These situations can all alter your deadline:
- Combined reporting
- Minimum taxes and estimated payments
- Short-period and final returns
- Foreign corporations
- Disaster relief
New York's CT-3-A and CT-33-A combined filers follow group and member-specific CT-5 rules, and some members must file separately.
Payment, Penalties, and Common Filing Mistakes
Federal and state consequences
Late filing and late payment are different charges.
- Late filing: generally 5% of unpaid tax per month or part-month, capped at 25%, reduced by any late-payment penalty for the same month.
- Late payment: 0.5% per month or part-month, capped at 25%.
- Interest: the IRS corporate underpayment rate is 7% for the fourth quarter of 2026, and 9% for large corporate underpayments, per the IRS interest notice.
- Estimated tax: instalments fall on the 15th day of months 4, 6, 9 and 12, and Form 2220 calculates the underpayment penalty.
States set their own charges. New York's late-filing penalty is 5% per month, capped at 25%. California and Texas publish their own penalty and interest schedules, so check each state's page.
Common mistakes
- Assuming Form 7004 covers every state
- Applying Form 1120-S rules to a Form 1120
- Missing a state minimum tax
- Overlooking nexus in a state where staff or sales sit
- Skipping the payment a state requires with an extension
- Treating an annual report as part of the tax extension
If you've missed a deadline
- File the overdue extension or return where the state permits.
- Pay as much as you can reasonably estimate.
- Save every confirmation.
- Review penalty relief. The IRS's First Time Abate looks at filing history, prior penalties and payment status, and reasonable cause looks at ordinary business care.
- Get state-specific professional advice.
2026 Filing Checklist and Next Steps
Preparation steps
- Identify every state where the corporation has employees, property, sales or other activity.
- Confirm the federal and state return forms for each state.
- Close the books for the tax year.
- Calculate estimated liability for each state.
- Gather prior filings and state account numbers.
- Submit Form 7004 and any state extensions by the original due date.
- Make required payments.
- Save confirmations.
Documents for Australian-owned corporations
- Ownership and related-party details
- Intercompany transaction records
- Apportionment data
- U.S. payroll and sales records
- Consolidated-group details, including Forms 851 and 1122 where relevant
- Information returns that may apply
Form 5472 is generally required for a 25%-foreign-owned U.S. corporation with reportable related-party transactions. The penalty is $25,000 for failing to file as required, with a further $25,000 if the failure continues more than 90 days after IRS notice.
FBAR applies separately where foreign accounts exceed $10,000 in aggregate.
BOI rules also changed: FinCEN's final rule exempts U.S. companies from BOI reporting, though some foreign companies registered to do business in the U.S. remain in scope.
Getting help
VJM Global's CPAs and chartered accountants support Australian businesses coordinating U.S. entity reporting, including federal, state and sales-tax obligations across multiple states. Confirm state-specific requirements with a qualified adviser before you file.
Frequently Asked Questions
Does Form 7004 automatically extend my state Form 1120 return?
No. Some states accept it, others require a separate form, and many attach payment conditions. Check each state's rules.
Do I need a separate state extension for a C corporation?
Often, yes. Connecticut and New York require their own forms, while Georgia, Delaware and Pennsylvania accept a valid federal extension.
Does a state tax extension give me more time to pay?
Generally no. It extends filing time only, and several states require a minimum payment by the original due date. Verify the amount and penalties.
When is the 2026 Form 1120 state extension due?
There is no single deadline. The date depends on the state, tax year, return type and whether the state follows the federal extension.
What happens if my corporation misses a state extension deadline?
Expect late-filing penalties, late-payment penalties and interest, and possibly a delinquent return. File and pay promptly to limit the exposure.
Do Australian-owned U.S. corporations need to file state extensions?
Ownership alone doesn't decide it. State nexus, activities, apportionment, entity structure and applicable forms determine each obligation.
