Two foreign corporations can file Form 1120-F on the same day and be in completely different positions. One filed on its original due date. The other filed under a regulatory extension and has been accruing interest for two months. A third, filing the same day a year later, may have forfeited every deduction it had. The rules that separate them are not intuitive, and IRS processing systems do not apply them correctly on their own.

Scope: this article covers foreign corporations filing Form 1120-F and, where the rules coincide, domestic corporations filing Form 1120. Individuals filing Form 1040 or Form 1040-NR run on their own due dates and extension rules and are covered in a companion article, Why Did the IRS Send a Late-Filing Penalty on a Return I Filed on Time?

Last updated: September 16, 2026

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Why does the IRS think the return was due April 15?

Because the fact that changes the answer is not on the return. Whether a foreign corporation maintains an office or place of business in the United States determines its due date, its extension route, and the date interest begins, and none of that is visible to the system that scores the filing. April 15 is the default. The return posts as two months late, the failure-to-file penalty generates automatically, and no examiner ever asks whether the deadline was right in the first place.

That is the most common cause, but several others produce the same outcome: a return filed on time under the law, scored as late by a system that never received the fact that would have changed the due date.

• US office status the IRS cannot see. The June 15 original due date under section 6072(c) depends on a factual absence, and nothing on the filed return establishes it.
• A fiscal year or short period scored against a calendar-year date. Short periods created by an acquisition, a liquidation, a dissolution, or a change in accounting period run from the end of the short period, and the resulting date is frequently not the one the system applies.
• A June 30 year end. For a corporation with a US office, Treasury Regulation 1.6072-2(a)(2) moves the deadline to the fifteenth day of the third month rather than the fourth, and treats a short period ending on any day in June as a taxable year ending June 30. The exception applies only to taxable years beginning before January 1, 2026, under the effective-date rules in P.L. 114-41 section 2006, so a June 30, 2026 year end is still due September 15, 2026, while a June 30, 2027 year end is the first to move to an October 15 original due date. Returns on either side of that line follow different rules.
• A Form 7004 the IRS never matched. An extension filed on time but posted to the wrong year, the wrong entity, or the wrong employer identification number leaves the account showing no extension at all. Name changes and post-merger successor entities are the usual culprits.
• A return the IRS never posted. Paper returns are lost, posted to the wrong period, or posted to a predecessor entity. The year then looks unfiled, and in some cases the IRS prepares a substitute for return.
• A mailing received after the deadline. Section 7502 treats a return as filed on the postmark date, but a private courier qualifies only if it is an IRS-designated delivery service using a designated service level, and a foreign postmark carries materially less protection than a US Postal Service one.
• An e-filed return rejected at the deadline. A rejected transmission can still be timely if it is corrected and retransmitted inside the perfection period, generally ten calendar days for business returns, but the retransmission date is sometimes what the IRS records.
• A disaster postponement that was never applied. Section 7508A relief posts automatically only where the address of record sits inside the covered area, so a corporation whose records or preparer are in the area, but whose address is not, can file within the postponement period and still receive a notice.
• The weekend and holiday rule. Section 7503 moves a deadline falling on a Saturday, Sunday, or legal holiday to the next business day.

When is Form 1120-F due for a foreign corporation with no US office?

The fifteenth day of the sixth month after the end of the tax year, June 15 for a calendar-year filer. That is an original statutory due date under section 6072(c), carried into Treasury Regulation 1.6072-2(b), not an extension, and the distinction drives everything else. A Form 7004 filed by June 15 runs the standard six months and carries the return to December 15. Section 6151(a) fixes payment at the time the return is due, determined without regard to any extension of time to file, so June 15 is also the payment date and interest does not begin before then. This corporation gets no June 30 fiscal-year exception; its date is the fifteenth day of the sixth month regardless of year end.

When is Form 1120-F due for a foreign corporation with a US office?

The fifteenth day of the fourth month, April 15 for a calendar-year filer, which puts this corporation on the same calendar as a domestic Form 1120 filer. Treasury Regulation 1.6072-2(a)(1)(i) sets that date for "a domestic C corporation (as defined in section 1361(a)(2)) or of a foreign C corporation having an office or place of business in the United States," and Treasury Regulation 1.6081-5(a)(3) then grants an automatic extension to June 15 for filing the return and for paying any tax shown on it. Form 7004 is otherwise due on the return due date itself; the Reg. 1.6081-5 exception is what permits filing it by June 15, and doing so adds four months from there, ending at October 15. The rest of the domestic corporate calendar comes with it: a new corporation filing a short-period return files by the fifteenth day of the fourth month after the short period ends, a dissolved corporation by the fifteenth day of the fourth month after the date it dissolved, and a June 30 fiscal year end moves to the fifteenth day of the third month.

October 15 is the end of the line. Treasury Regulation 1.6081-1(b)(1) generally bars a discretionary extension longer than the applicable automatic extension, and the six-month corporate extension in section 6081(b) is measured from the statutory return date, which for this corporation is April 15. Nothing on Form 7004 reaches past October 15, and there is no separate corporate procedure for requesting more time.

When does interest start, and is that the same as the time to pay?

They are not the same thing, and conflating them is how a corporation ends up surprised by an interest computation on a balance it thought was timely paid. An extension of time to pay stops the failure-to-pay penalty under section 6651(a)(2) from beginning until the extended date. Interest is governed separately by section 6601, and section 6601(b)(1) determines the last date prescribed for payment without regard to any extension granted for payment.

Applied to the two regimes, the corporation with no US office has the better position. June 15 is its statutory due date, so under section 6151(a) it is also the payment date, and both interest and the failure-to-pay penalty start June 15. The corporation with a US office is fixed at April 15. Reg. 1.6081-5(a) extends its time to pay to June 15, so the failure-to-pay penalty does not begin until then, but interest accrues from April 15 anyway. Same filing date, two months of interest apart. Two further limits apply to that extension: Reg. 1.6081-5(b) conditions it on attaching a statement to the return showing which category applies, and it reaches only tax shown on the return, so tax surfacing on a later adjustment sits outside it entirely. Estimated tax is a separate track in both cases, since the section 6655 addition to tax runs from the quarterly installment dates regardless of when the return is due.

What happens if the return is filed more than 18 months late?

This is where a due-date error stops being a penalty problem and becomes an existential one. Section 882(c)(2) conditions a foreign corporation's deductions and credits on filing a true and accurate return. Treasury Regulation 1.882-4(a)(3)(i) supplies the deadline: where the corporation filed a return for the immediately preceding taxable year, or the current year is the first year for which a return is required, "the required return for the current taxable year must be filed within 18 months of the due date as set forth in section 6072 and the regulations under that section, for filing the return for the current taxable year." Past that point the IRS can assess tax on gross US-source income with no deductions allowed, which can produce a liability many times the tax on net income. The regulation permits a waiver where the corporation establishes, on the facts and circumstances, that it acted reasonably and in good faith in failing to file, so a late return should be filed with that showing rather than filed silently and hoped over.

Key dates at a glance

How much do these penalties cost?

The penalty on the return itself is usually the smallest piece. The information returns that travel with a corporate filing carry fixed penalties that have nothing to do with how much tax is at stake:

• Form 5472. Section 6038A(d) imposes $25,000 per form, per year, for each reporting corporation, plus continuation penalties of up to $25,000 for each 30-day period after IRS notice. A corporation with several related-party categories to report files several forms.
• Form 5471. Section 6038(b) imposes $10,000 per form, per year, per foreign corporation, plus continuation penalties of up to $50,000 if the failure persists after notice.
• Form 8865. Section 6038(b) imposes $10,000 per form, per year, per foreign partnership, with the same continuation structure.
• Failure to file. Section 6651(a)(1) imposes 5% of the unpaid tax for each month the return is late, capped at 25%.
• Loss of deductions. Not a penalty at all, and usually the largest number on the page. See the 18-month rule above.

A structure with a handful of related-party reporting obligations can carry six figures of information return exposure on a return that was filed on its correct statutory due date. The notice arrives with a payment stub and a 30-day clock, which is why so many of these get paid rather than contested.

What relief is available?

A notice is an opening position, not a final assessment. Four pathways exist, and more than one often applies to the same account. They are listed strongest first.

• Proof of timely filing. The strongest position available, because it is not a request for leniency. That takes two things, and most responses supply only the second. Cite the authority that sets the deadline, whether that is section 6072(c), Treasury Regulation 1.6072-2, Treasury Regulation 1.6081-5, or section 7508A, and then prove the facts that make it apply. The person reading your response is working from an account that says the return was late, and an assertion that it was timely, unsupported by the provision that makes it so, reads as a disagreement rather than a correction.
• First-Time Abate, now the Automatic Exemption from Penalty. An administrative waiver for filers with a clean compliance history over the prior three years who have filed or extended all currently required returns and paid or arranged to pay any tax due. It reaches failure-to-file, failure-to-pay, and failure-to-deposit penalties and requires no explanation of why the failure occurred. The IRS is automating this waiver and renaming it the Automatic Exemption from Penalty, applying it during return processing rather than after assessment.
• Reasonable cause. Relief grounded in facts showing ordinary business care and prudence. In cross-border corporate cases the recurring grounds are inability to obtain records held by a foreign institution or affiliate, reliance on a qualified adviser, a change in control or personnel that severed the compliance function, and disruption at a foreign accounting or legal provider.
• Statutory exceptions. Relief that applies by operation of law, including certain IRS errors and reliance on written advice furnished by the IRS in response to a specific request.

Some of this is now automatic. Under the Automatic Exemption from Penalty the IRS suppresses covered penalties at processing for eligible filers and sends a notice confirming it, with no request required. That does not extend to everything on this list. Proof of timely filing, reasonable cause, and the statutory exceptions still require you to raise them, and information return penalties under sections 6038 and 6038A fall outside the exemption as they did outside First-Time Abate. Worth keeping in view: a penalty that was wrongly assessed in the first place, on a return that was timely under the correct deadline, should be reversed on that basis rather than absorbed as a waiver, since the waiver is available only once per compliance cycle and a corporation with recurring international filings will want it later. The current standards are set out in the IRS guidance on penalty relief and on reasonable cause.

What proof does the IRS want?

The central exhibit is whatever establishes the corporation's US office status during the year, since that is the fact the IRS never had. Depending on the structure, that can be lease and property records, payroll and personnel records, board and management records showing where activity occurred, and the transfer pricing or treaty documentation already prepared for other purposes. Add the filing receipt, any Form 7004 with its acknowledgment, and the account transcript, which matters as much as the return itself because it shows the due date the IRS actually used and the transaction code that generated the penalty. Assembling that record into a short, precise response, addressed to the unit that can act on it, is what separates a reversal from a form-letter denial.

Frequently asked questions

Does Form 7004 extend a Form 1120-F to December 15 or October 15?

It depends on the original due date. For a foreign corporation with no US office, June 15 is the original date and the six-month extension runs to December 15. For a foreign corporation with a US office, April 15 is the original date, so the extension ends at October 15 even though the Form 7004 itself is filed by June 15 under the Reg. 1.6081-5 exception.

Can a foreign corporation with a US office extend past October 15?

No. Treasury Regulation 1.6081-1(b)(1) generally bars a discretionary extension longer than the applicable automatic extension, and the corporate automatic extension in section 6081(b) is six months measured from the statutory return date, which is April 15 for this corporation. There is no further filing extension available on Form 7004 or by request.

Does the extension to June 15 also extend a foreign corporation's time to pay?

For the corporation with a US office, yes as to tax shown on the return, because Reg. 1.6081-5(a) grants the extension "for filing returns of income and for paying any tax shown on the return." Interest still runs from April 15 under section 6601(b)(1). For the corporation with no US office there is nothing to extend, because June 15 is the original due date and section 6151(a) fixes payment on that date.

When does interest start for a foreign corporation with no US office?

June 15. Section 6151(a) sets the payment date at the time the return is due, and section 6601 runs interest only from the last date prescribed for payment. The estimated tax addition under section 6655 is separate and runs from the installment dates.

What happens if a Form 1120-F is filed more than 18 months late?

Treasury Regulation 1.882-4(a)(3)(i) requires the return to be filed within 18 months of the due date set by section 6072, and 1.882-4 permits the IRS to disallow all deductions and credits and tax gross US-source income when it is not, which can produce a liability far larger than the tax on net income. The regulation allows a waiver where the corporation establishes that it acted reasonably and in good faith, so a late filing should be accompanied by that showing rather than filed silently.

Should a corporation file a protective Form 1120-F if it believes it has no US trade or business?

It is worth serious consideration. A protective return preserves the ability to claim deductions and credits if the IRS later determines that effectively connected income existed, and the 18-month clock runs from the original due date whether or not the corporation thought it had a filing obligation.

Does a June 30 fiscal year end change the Form 1120-F deadline?

For a corporation with a US office, yes. Treasury Regulation 1.6072-2(a)(2) provides that the return is due the fifteenth day of the third month rather than the fourth, and that a short period ending on any day in June is treated as a taxable year ending June 30. It applies only to taxable years beginning before January 1, 2026, under the effective-date rules in P.L. 114-41 section 2006, so a June 30, 2026 year end is still due September 15, 2026 and a June 30, 2027 year end is the first to follow the ordinary fourth-month schedule. A corporation with no US office has no equivalent exception.

The corporation dissolved mid-year. When is the final return due?

For a corporation with a US office, the fifteenth day of the fourth month after the date it dissolved. Short-period and final returns are among the most common sources of wrong-due-date notices, because the correct date is not a calendar-year date and systems tend to score them against one.

Does the first-time waiver cover a Form 5472 penalty?

Not directly. IRM 20.1.9.5.5 provides that a Form 5472 penalty systemically assessed when the form is attached to a late-filed return may be relieved where the failure-to-file penalty on the underlying return is abated under First-Time Abate, or would have been eligible for it had a penalty been assessed. Whether that derivative relief survives the move to the Automatic Exemption from Penalty is unresolved, because the exemption suppresses the penalty at processing rather than abating it afterward.

Can a corporate penalty be removed over the phone?

Sometimes, and the rules here have moved more than once. Account corrections, including a due date the IRS scored wrong, are frequently resolved on a single call and can post within days. Information return penalties and anything requiring documentary proof need a written response with exhibits. Confirm the current procedure before relying on a call.

What if the corporation already paid the penalty?

Payment does not forfeit the claim. You can request abatement and a refund of the amount paid, subject to the refund limitations in section 6511, generally three years from the date the return was filed or two years from the date of payment, whichever is later.

Does this apply to a foreign partnership, an individual, or a domestic corporation?

Partly. A domestic corporation filing Form 1120 shares the fourth-month date, the June 30 exception, and the short-period and dissolution rules described here, but not the Reg. 1.6081-5 extension unless it keeps its books outside the United States. A foreign partnership filing Form 1065 runs on its own dates and is outside this article. Individuals filing Form 1040 or Form 1040-NR are covered in the companion article on late-filing notices issued on returns filed on time.

Have a notice in hand? Tell us about it.

Form 1120-F deadlines are easy to misread, and the IRS misreads them regularly. If a late-filing notice arrived on a return filed on its correct statutory date, if an extension was never matched to the account, or if a return is approaching the 18-month line where deductions are at stake, the correct due date can be confirmed, the proof assembled, and the response prepared. Notices carry response deadlines, so the earlier the notice is reviewed, the more paths remain available. If the notice is addressed to an individual rather than to the corporation, start with the companion article covering Form 1040 and Form 1040-NR filers instead.

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This article is provided for general informational and marketing purposes only and does not constitute legal, tax, or accounting advice. Statutes, regulations, deadlines, and penalty amounts change, and outcomes depend on the specific facts of each matter. Do not act or refrain from acting on the basis of this content without advice from a qualified professional. Reading this article or contacting the author does not create a client relationship.