When Is Form 1120 Due for Delaware Companies?

A missed federal filing date can create a costly problem long before an owner realizes a return was required. If you are asking when is Form 1120 due, the standard answer is the 15th day of the fourth month after the end of the corporation’s tax year. For most Delaware corporations using a calendar year, that means April 15.

That date is only the starting point. Foreign-owned Delaware businesses must first confirm whether Form 1120 is actually their required return, whether Form 5472 must be attached, and which separate Delaware deadlines also apply. Entity classification, ownership, and the company’s fiscal year all affect the compliance calendar.

When is Form 1120 due for a calendar-year corporation?

A domestic C corporation that ends its tax year on December 31 generally must file Form 1120 by April 15 of the following year. Form 1120 is the U.S. Corporation Income Tax Return. It reports the corporation’s income, deductions, tax liability, balance sheet information, and other required disclosures.

For example, a Delaware C corporation with a December 31, 2025 year-end generally files its 2025 Form 1120 by April 15, 2026. If the deadline falls on a weekend or federal holiday, the due date moves to the next business day.

The return deadline is not merely an administrative date. A C corporation that owes federal income tax should pay its tax by the original due date, even if it requests more time to file. An extension delays the filing requirement, not the payment requirement.

Form 1120 due dates for fiscal-year corporations

Not every corporation uses a December 31 year-end. A corporation may have a fiscal year that ends in another month, subject to applicable tax rules and the entity’s established accounting period.

For most fiscal-year C corporations, Form 1120 is due on the 15th day of the fourth month after the tax year ends. A company with a September 30 year-end, for instance, generally has a January 15 filing deadline.

There is a notable exception for corporations with tax years ending on June 30. Those corporations generally file Form 1120 on the 15th day of the third month after year-end, which is typically September 15. This exception can matter for established businesses with non-calendar fiscal years, so do not assume every corporation has four months after year-end.

Accurate bookkeeping makes this process far more manageable. The return is built from the company’s actual financial records, including revenue, expenses, owner transactions, assets, liabilities, and tax payments. Waiting until the filing deadline to organize records often increases both cost and risk.

Can you extend the Form 1120 deadline?

Yes. A corporation can generally request an automatic six-month extension by filing Form 7004 on or before the original Form 1120 due date. For a calendar-year corporation, a timely Form 7004 typically moves the filing deadline from April 15 to October 15.

The extension is useful when financial statements are incomplete, information is still being collected from overseas owners, or the corporation needs more time to finalize tax calculations. It is not a substitute for planning. The corporation must estimate its federal tax liability and pay the expected balance by the original deadline.

If tax remains unpaid, interest and possible late-payment penalties may continue to accrue. A company that expects no taxable income may still need to file Form 1120 or an extension, depending on its classification and reporting obligations.

Foreign-owned LLCs may need Form 1120 and Form 5472

This is where many international entrepreneurs become confused. A single-member Delaware LLC owned by a non-U.S. person is often treated as a disregarded entity for U.S. federal income tax purposes. In many cases, it does not file a full Form 1120 as a C corporation would.

However, a foreign-owned U.S. disregarded entity can be required to file a pro forma Form 1120 with Form 5472 attached. Form 5472 reports certain transactions between the LLC and its foreign owner or other related parties. These transactions can include capital contributions, distributions, loans, management charges, and payments made on the company’s behalf.

For these foreign-owned LLCs, the Form 5472 filing is generally due by the Form 1120 deadline. A calendar-year foreign-owned LLC commonly has an April 15 due date, and Form 7004 can generally extend both filings when submitted on time.

The penalty exposure deserves careful attention. Failure to file a required Form 5472 correctly and on time can trigger a $25,000 penalty, with additional penalties possible if the failure continues after IRS notice. This penalty can apply even when the LLC had little activity, no profit, or no U.S. income tax due.

A zero-income year does not automatically mean a zero-filing year. For foreign-owned entities, compliance depends on the legal structure and transactions, not simply whether the business made a profit.

Does every Delaware LLC file Form 1120?

No. A Delaware LLC does not automatically file Form 1120. Federal filing requirements depend on how the LLC is classified for tax purposes.

A single-member LLC may be treated as a disregarded entity. If its sole owner is foreign, it may have the Form 5472 and pro forma Form 1120 requirement described above. A multi-member LLC is generally treated as a partnership unless it elects otherwise, and it commonly files Form 1065 rather than Form 1120. A Delaware LLC that elects to be taxed as a C corporation generally files Form 1120.

A Delaware corporation formed as a C corporation normally files Form 1120, even if all owners live outside the United States. Foreign ownership does not remove the corporation’s U.S. federal filing responsibilities.

Because classification determines the return, founders should not rely on the word “LLC” or “corporation” in casual business discussions. Review the entity’s formation documents, tax elections, ownership structure, EIN records, and prior filings before choosing a deadline.

Form 1120 is separate from Delaware tax deadlines

Federal and Delaware obligations are separate. Filing Form 1120 with the IRS does not satisfy Delaware franchise tax, annual report, or Delaware income tax filing requirements.

Delaware C corporations generally must file an annual report and pay Delaware franchise tax by March 1 each year. This deadline can arrive before a calendar-year Form 1120 is due. The franchise tax is based on Delaware corporate rules and is not the same as federal corporate income tax.

Delaware LLCs generally do not file an annual report, but they must typically pay the Delaware LLC annual tax by June 1. This obligation applies regardless of whether the LLC had income or conducted business during the year.

A Delaware corporation may also have a Delaware corporate income tax filing requirement, particularly if it conducts business or earns income connected with Delaware. In addition, companies operating outside Delaware may create tax filing obligations in other states. Incorporation in Delaware does not limit a business’s compliance responsibilities to Delaware alone.

What happens if Form 1120 is filed late?

For a C corporation with unpaid tax, the IRS can impose a late-filing penalty generally calculated as a percentage of unpaid tax for each month or part of a month the return is late, up to a maximum limit. Interest may also apply to unpaid tax and penalties.

The financial consequences can be more severe for a foreign-owned disregarded LLC that misses a required Form 5472. As noted above, the initial penalty is generally $25,000. The IRS may also request records supporting reportable related-party transactions, and incomplete records can create additional compliance issues.

Late filing also creates practical problems. It can delay financial reporting, complicate investor or banking requests, and make it harder to establish a clean compliance history for a growing U.S. business.

A practical filing calendar for foreign-owned businesses

For many calendar-year Delaware companies, the key dates are March 1 for Delaware C corporation franchise tax and annual reports, April 15 for Form 1120 and many Form 5472 filings, June 1 for Delaware LLC annual tax, and October 15 for an extended calendar-year Form 1120 filing.

Those dates are not universal. A fiscal-year corporation, a partnership-taxed LLC, an entity with special elections, or a business operating in several states may have a different calendar. The most reliable approach is to establish the company’s tax classification and year-end early, then maintain books throughout the year that support every required return.

The best time to resolve a Form 1120 question is before the deadline becomes urgent. A clear filing calendar and current records give business owners the confidence to focus on operations while their U.S. compliance stays on track.