Form 1120-F: when a foreign corporation files a US return

A foreign corporation does not file a US return simply because it exists abroad — it files Form 1120-F when it has the right kind of connection to the United States. Working out whether that connection exists, and how the resulting income is taxed, is the heart of the matter, because the US taxes a foreign corporation's US-connected business income quite differently from its passive US-source income. This guide sets out when the return is required and how the tax works.

When the return is required

A foreign corporation generally must file Form 1120-F, the U.S. Income Tax Return of a Foreign Corporation, if any of the following is true for the year:

• It was engaged in a trade or business in the United States, whether or not it had income from that activity and whether or not a treaty protects the income.
• It had income that was effectively connected with a US trade or business.
• It had certain US-source income on which the full US tax was not satisfied by withholding at source.

There is also a protective return: a foreign corporation that believes it is not engaged in a US trade or business, but cannot be certain the IRS will agree, may file a protective Form 1120-F to preserve its ability to claim deductions and credits if the position is later challenged. Without a timely return, those deductions can be lost, so the protective filing is a defensive step rather than an admission of a US business.

How the US income is taxed

The tax splits along the same fault line as it does for individuals. Effectively connected income is taxed on a net basis — after deductions — at the flat 21% corporate rate, in the same way a domestic C corporation is taxed on its profit, as described in Form 1120. Layered on top is the branch profits tax: a further tax, generally at 30% (or a reduced treaty rate), on the corporation's effectively connected earnings treated as repatriated out of the US branch. Its purpose is to approximate the second layer of tax a US subsidiary would bear when it pays a dividend to its foreign parent. Separately, passive US-source income of the FDAP kind is generally taxed at 30% at source through withholding, outside the net-basis return.

Deadline and treaty positions

The due date turns on whether the foreign corporation maintains an office or place of business in the US. One that does generally files by the 15th day of the fourth month after year-end, with an automatic extension available under the extension regulations; one that does not generally files by the 15th day of the sixth month. Because the rule is fact-specific, the exact date should be confirmed from the instructions. Treaty positions are central to Form 1120-F: a treaty may reduce the branch profits rate, or provide that business profits are only taxable in the US to the extent attributable to a permanent establishment, and such positions are disclosed on the return.

Corporation, not individual

It is worth being clear about which return applies. A foreign corporation with US-connected income files Form 1120-F; a foreign individual files Form 1040-NR. And a US LLC that is foreign-owned has its own information-reporting overlay regardless of income — see Form 5472 — which is a separate obligation from the income tax return itself. Because these regimes interact, a foreign business with any US footprint benefits from mapping its structure before assuming which returns it must file.

An evidence-led way to apply this guidance

The useful question in Form 1120-F: when a foreign corporation files a US return is not simply whether a rule exists. For Form 1120-F: when a foreign corporation files a US return, the file must prove the facts that make the rule apply. Start the Form 1120-F: when a foreign corporation files a US return working by writing down entity classification, filing status, state exposure, information returns and the payment trail. Then tie each Form 1120-F: when a foreign corporation files a US return conclusion to formation documents, federal and state notices, bank statements, contracts and filed forms. That article-specific exercise separates a defensible Form 1120-F: when a foreign corporation files a US return position from one built around a label, a memory or a copied rate.

The legal starting point for Form 1120-F: when a foreign corporation files a US return is Internal Revenue Code § 11, Subchapter S where relevant, and the current IRS form instructions. The operational check for Form 1120-F: when a foreign corporation files a US return belongs with the IRS and the relevant state authority. Read the instrument, current guidance and actual transaction together for Form 1120-F: when a foreign corporation files a US return: guidance explains administration, but it does not rewrite the law or repair missing evidence.

No decorative rate. Form 1120-F: when a foreign corporation files a US return is primarily a classification and evidence question, so this case file uses amounts to demonstrate the decision without inventing a percentage that the governing rules do not supply. That restraint is deliberate for Form 1120-F: when a foreign corporation files a US return: an irrelevant percentage would make the page look detailed while making the advice less reliable.

Two worked case files

Worked example 1 — bridge business records to the federal filing position. For a file concerning Form 1120-F: when a foreign corporation files a US return, assume the records show USD 700,000 as the gross business receipts in the books, USD 80,000 as the documented deductible operating costs, and USD 35,000 as the book item requiring a tax or entity adjustment. The amount carried to the filing workpaper for Form 1120-F: when a foreign corporation files a US return is therefore USD 585,000:

WORKING 1 USD 700,000 - USD 80,000 - USD 35,000 = USD 585,000

The arithmetic is the easy part of Form 1120-F: when a foreign corporation files a US return. The Form 1120-F: when a foreign corporation files a US return judgement sits in federal classification, state nexus, form selection, owner reporting and the support for each adjustment, including why USD 80,000 and USD 35,000 were removed. If any Form 1120-F: when a foreign corporation files a US return answer is weak, keep the amount in the exception list rather than forcing it into a filing, resolution or account.

Worked example 2 — reconcile federal, state and cash records. For Form 1120-F: when a foreign corporation files a US return, assume USD 900,000 as the combined federal and state control total, USD 150,000 as the payments and withholding already credited, and USD 45,000 as the documented state or timing differences. The open balance before the return is signed for Form 1120-F: when a foreign corporation files a US return is USD 705,000.

WORKING 2 USD 900,000 - USD 150,000 - USD 45,000 = USD 705,000

For Form 1120-F: when a foreign corporation files a US return, place the USD 900,000 combined federal and state control total, the USD 150,000 support for the payments and withholding already credited, and the USD 45,000 schedule for the documented state or timing differences beside the final USD 705,000 balance. A Form 1120-F: when a foreign corporation files a US return reviewer should be able to move from source evidence to control total, from control total to decision, and from decision to the submitted figure without a hidden spreadsheet or oral explanation.

The final quality-control questions

• Has the file for Form 1120-F: when a foreign corporation files a US return identified the controlling law and the version effective for the relevant date?
• Are the Form 1120-F: when a foreign corporation files a US return assumptions visibly labelled and separated from enacted rates, thresholds and deadlines?
• Do the USD 585,000 and USD 705,000 results reconcile to source evidence and the general ledger?
• Is every Form 1120-F: when a foreign corporation files a US return exception assigned to a person and date rather than buried in a note?
• Has the client or responsible officer approved the Form 1120-F: when a foreign corporation files a US return facts before submission?

This is the standard that makes Form 1120-F: when a foreign corporation files a US return useful in practice: the conclusion is stated, the law is named, the numbers can be recomputed, and the evidence survives after the person who prepared the file has moved on.

Sources

This guide is written against the official and clearly labelled professional references below. Rates, thresholds and portal procedures change between reviews, so open the primary source before relying on a figure.

• About Form 1120-F, U.S. Income Tax Return of a Foreign Corporation (IRS)
• Corporations (IRS)
• Businesses (Internal Revenue Service)

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