Do I have to file Form 5471 if my British husband owns the UK company and I hold no shares?

Usually not. For the CFC and US shareholder tests, section 958(b)(1) blocks attribution of stock owned by a nonresident alien to a US citizen or resident, so his shares are not treated as yours for Category 5. For the Category 4 control test his shares are attributed to you, but the IRS exception in Regulations section 1.6038-2(l) removes the filing requirement where you own no direct or indirect interest and are caught solely by constructive ownership from a nonresident alien. Category 3 can still be triggered by certain events, so review any year in which you acquire shares.

Are my brother's shares in our family company attributed to me for Form 5471?

Not for the main tests. Section 318(a)(1) covers only a spouse, children, grandchildren and parents, so siblings are excluded for the CFC, US shareholder and Category 4 control tests. The exception is Categories 2 and 3. Section 6046(c) and Regulations section 1.6046-1(i) define family to include brothers and sisters of the whole or half blood, a spouse, ancestors and lineal descendants, so a sibling's holding can count when testing an acquisition, a disposal or an officer or director filing for that year.

My British parents own 60% of the family company and I own 5%. Am I a Category 4 filer?

Very likely yes. For Category 4, section 6038(e)(2) applies section 318(a) family attribution without the nonresident alien exception, so you are deemed to own your 5% plus your parents' 60%, or 65%, which is control. The nonresident alien filing exception only helps a person who owns no direct or indirect interest, and your 5% direct holding rules it out. Whether the company is also a CFC is a separate question, answered under section 958(b), where your parents' shares are ignored because they are nonresident aliens.

Did the 2025 legislation end downward attribution for Form 5471?

For most purposes, going forward. Public Law 119-21, the One Big Beautiful Bill Act, restored section 958(b)(4) for taxable years of foreign corporations beginning after December 31, 2025, so a US person is again not treated as owning stock held by a foreign person through downward attribution for the CFC tests. It does not change earlier years, and it added section 951B, which can still apply income inclusions to a US person that would own more than 50% if the limit were disregarded. Category 4 control has always excluded this type of attribution under section 6038(e)(2).

Can one family member file a single Form 5471 for everyone?

Often, yes. The Form 5471 instructions allow one person with the same or greater filing requirements to file a joint return covering others who must report the same company for the same period. Everyone named in item H attaches a statement to their own return and, for Categories 1a, 1b, 4, 5a and 5b, a separate Schedule P. Family members caught only through constructive ownership from a US relative who files a complete return may not need to file at all. Category 5b and 5c filers cannot file jointly, and each person remains liable if the joint return is wrong.

What should I do if I missed Form 5471 for years because of family attribution?

First confirm the requirement actually existed, testing each year under the correct attribution rules and checking the Rev. Proc. 2019-40 relief for downward-attribution years. If returns were required and no tax was underreported, the Delinquent International Information Return Submission Procedures let you file with a reasonable cause statement, provided you are not under examination. If income or FBARs were also missed and the failure was non-willful, the Streamlined Foreign Offshore Procedures cover three years of returns with Form 5471 and six years of FBARs without penalties for eligible filers living outside the US.

Form 5471 Family Attribution: UK Families and Section 318

Form 5471 can be required from a US citizen who holds few or no shares in a UK family company, because the Internal Revenue Code treats you as owning shares that certain relatives hold. Under section 318(a)(1), an individual is deemed to own stock owned by a spouse, children, grandchildren and parents, but not stock owned by brothers, sisters, grandparents or in-laws. For the controlled foreign corporation tests, section 958(b)(1) switches that family attribution off where the relative is a nonresident alien, which is why an American married to a British spouse is usually not treated as owning the spouse's shares for CFC purposes. The same shares can still count for the Category 4 control test and the Category 3 acquisition test, and that difference is where most family filing errors begin.

This guide works from sections 318, 958, 6038 and 6046 of the Internal Revenue Code and the December 2025 revision of the IRS Instructions for Form 5471, the current version on IRS.gov as of September 2026, and finishes with a worked family tree showing who is deemed to own what.

What is Form 5471 and why does family ownership matter?

Form 5471 is the IRS information return that certain US citizens, residents, domestic partnerships and domestic corporations file to report their interest in a foreign corporation, including a UK private limited company. It is filed with the US income tax return and asks for the company's shareholders, balance sheet, income statement, earnings and profits and transactions with related parties, translated into US dollars. The IRS sorts filers into five categories, and every threshold test in those categories is measured by direct, indirect and constructive ownership.

Constructive ownership is a legal fiction under which you are treated as owning shares registered to someone else. In a UK family company, where relatives hold blocks of 10% to 40% each, it routinely pushes a US family member over the 10% or more-than-50% lines. The catch is that the Code uses three different sets of attribution rules, depending on which Form 5471 category you are testing.

Category 1 and Category 5 (US shareholders of a section 965 specified foreign corporation or of a controlled foreign corporation) use section 958(b), which applies section 318(a) with modifications, including the nonresident alien family exception.
Category 4 (control of more than 50% of the vote or value) uses section 6038(e)(2), which applies section 318(a) with only two modifications and no nonresident alien family exception.
Category 2 and Category 3 (officers, directors, and acquisitions or disposals around the 10% line) use section 6046(c) and Regulations section 1.6046-1(i), which define family more broadly, adding brothers and sisters and all ancestors.

Which family members count under section 318(a)(1)?

Section 318(a)(1) is the core family attribution rule. It provides that an individual is considered as owning the stock owned, directly or indirectly, by or for a spouse, children, grandchildren and parents. A spouse who is legally separated under a decree of divorce or separate maintenance is excluded. Age is irrelevant: a 45-year-old son and his 70-year-old father attribute shares to each other just as a minor child and parent would.

Counted: your spouse, unless legally separated under a decree of divorce or separate maintenance.
Counted: your children, including adult children, and your grandchildren.
Counted: your parents.
Not counted: your brothers and sisters, whether of the whole or half blood.
Not counted: your grandparents. The rule is one-directional, so a grandchild's shares are attributed up to the grandparent, but the grandparent's shares are not attributed down to the grandchild.
Not counted: aunts, uncles, nieces, nephews and cousins.
Not counted: in-laws, including a spouse's parents, a spouse's siblings and a child's spouse.

Section 318(a)(5)(B) adds a rule that stops the chain. Stock that an individual constructively owns because of family attribution is not treated as owned by that individual for the purpose of applying family attribution again. So if your father's shares are attributed to you, they cannot then be passed from you to your husband or wife. This is why in-laws never count, even indirectly through the spouse.

The broader family definition used for Categories 2 and 3 is different. Section 6046(c) says the family of an individual includes only brothers and sisters, whether by the whole or half blood, spouse, ancestors and lineal descendants, and Regulations section 1.6046-1(i) applies the same list with its own no-chaining rule. For the acquisition and officer-and-director tests, therefore, a sibling's shares and a grandparent's shares do count. In-laws still do not.

Why is a British spouse's shareholding usually ignored for Form 5471 CFC tests?

A controlled foreign corporation is a foreign corporation in which US shareholders own, directly, indirectly or constructively within the meaning of section 958(a) and (b), more than 50% of the total combined voting power or more than 50% of the total value of the stock on any day of the foreign corporation's tax year. A US shareholder is a US person who owns 10% or more of the vote or value, measured the same way.

Section 958(b) imports section 318(a) for these tests, but its first modification is the one that protects most internationally married families. In applying section 318(a)(1)(A), stock owned by a nonresident alien individual is not considered as owned by a citizen or by a resident alien individual. The exception applies to every relative in the family rule. A British spouse, British parents, and British children or grandchildren who are nonresident aliens do not pass their shares to the American family member for the US shareholder and CFC tests.

Two limits matter. First, section 958(b)(1) only blocks attribution from nonresident alien individuals; shares held by a relative who is a US citizen, green card holder or substantial-presence resident are attributed in full. Second, that status can change. The Category 4 definition of a US person in the Form 5471 instructions expressly includes a nonresident alien covered by a section 6013(g) election, the election that lets a US citizen file jointly with a nonresident spouse, so model the spouse's shareholding before making it.

Does a nonresident relative's stake still count for Form 5471 Categories 3 and 4?

Yes. Section 6038(e)(2) defines control for Category 4 as owning stock with more than 50% of the total combined voting power or more than 50% of the total value, and it says the rules of section 318(a) apply with only two exceptions: no downward attribution from a non-US person to a US person, and 10% substituted for 50% in the corporate attribution rule. There is no nonresident alien family exception. A British spouse's or British parent's shares are therefore counted when you test whether you control the UK company.

The IRS softens this with a filing exception rather than a change to the ownership rule. Under Regulations section 1.6038-2(l), as summarised in the Form 5471 instructions, a Category 4 filer (and likewise a Category 1 or Category 5 filer) does not have to file if it does not own a direct or indirect interest in the foreign corporation and is required to file solely because of constructive ownership from a nonresident alien. The weakness is the first condition: owning even one share directly takes you outside it, so a US family member with a small direct holding plus British relatives above 50% is a full Category 4 filer.

Category 3 has no nonresident alien exception. Its only constructive-owner exception requires that the filer holds no direct interest and is caught solely through another US person who files a complete Form 5471. Because section 6046 counts siblings, spouses, ancestors and lineal descendants with no carve-out for nonresidents, a share subscription, a disposal below 10% or a relative becoming a US person can create a Category 3 return even when no Category 5 return exists.

How does entity attribution work for family holding companies and partnerships?

Many British families hold their trading company through a holding company or a family partnership, and section 318 moves ownership through those entities in both directions. Upward, section 318(a)(2)(A) treats stock owned by a partnership as owned proportionately by its partners, and section 318(a)(2)(C) treats stock owned by a corporation as owned proportionately by any shareholder holding 50% or more in value, a threshold that section 958(b) and section 6038(e)(2) both lower to 10%. Downward, section 318(a)(3)(A) treats a partnership as owning its partners' stock, and section 318(a)(3)(C) treats a corporation as owning the stock of any person holding 50% or more of it.

Family and entity rules stack. If your US-citizen mother owns 40% of a UK family holding company and you own 20%, family attribution gives you her 40%, and your deemed 60% then carries a proportionate share of every subsidiary the holding company owns into your Form 5471 analysis.

What happened to downward attribution between 2018 and 2026?

Section 958(b)(4) provides that subparagraphs (A), (B) and (C) of section 318(a)(3) shall not be applied so as to consider a US person as owning stock owned by a person who is not a US person. The Tax Cuts and Jobs Act of 2017 struck that paragraph, so downward attribution from foreign owners applied for the CFC tests. A UK family group that owned a US subsidiary could find the subsidiary deemed to own the family's other UK companies, turning them into CFCs and pulling US relatives with 10% indirect holdings into Category 5. The IRS responded with Rev. Proc. 2019-40, which introduced the Category 5b and 5c reporting relief for foreign-controlled CFCs and penalty relief in its section 7.

Public Law 119-21 of July 4, 2025, commonly known as the One Big Beautiful Bill Act, re-added section 958(b)(4) through section 70353, for taxable years of foreign corporations beginning after December 31, 2025, with no inference for earlier years. A UK company with a 31 March year end is under the restored rule for its year beginning 1 April 2026, but its year beginning 1 April 2025 is still tested under the old rule.

The same law added section 951B for the same years. It applies the subpart F and section 951A inclusion rules to a foreign controlled United States shareholder, broadly a US person that would be a US shareholder at a more-than-50% threshold if the section 958(b)(4) limit were disregarded. For most UK families it matters only where a US company sits under a British parent. The December 2025 instructions do not yet explain how section 951B inclusions are reported, so check the Future Developments page for Form 5471 on IRS.gov before preparing 2026 returns.

Worked example: who is deemed to own what in a UK family company?

Consider a hypothetical UK trading company, Hartley Holdings Ltd, with one class of ordinary shares and a calendar year end. Its register of members shows the following.

Richard, the founder, British nonresident alien: 30%.
Margaret, Richard's wife, British nonresident alien: 10%.
Emma, their daughter, US citizen living in London: 15%.
Oliver, Emma's husband, British nonresident alien: 10%.
James, Emma's brother, US citizen living in New York: 5%.
David, Richard's brother, US citizen living in Boston: 15%.
Oliver's father, British nonresident alien: 15%.

Step one is the CFC test under section 958(b). Only US persons can be US shareholders, and family attribution from Richard, Margaret, Oliver and Oliver's father is blocked by section 958(b)(1) because they are nonresident aliens. Emma and James are siblings, and David is their uncle, so nothing is attributed among the three Americans. Emma owns 15% and David owns 15%, making each a US shareholder. James owns 5% and is not. US shareholders hold 30% in total, well short of the more-than-50% line, so Hartley Holdings is not a CFC and nobody is a Category 5 filer.

Step two is the Category 4 control test under section 6038(e)(2), where nonresident family members count. Emma is deemed to own her own 15%, her husband Oliver's 10%, and her parents' 30% and 10%, a total of 65%. Her father-in-law and her brother are ignored. Emma controls the company, and because she owns shares directly the nonresident alien exception is unavailable, so she files Form 5471 as a Category 4 filer every year. James is deemed to own 5% plus his parents' 40%, or 45%, which is not control. David owns only his 15%, because his brother Richard is outside the family rule.

Now change one fact. Richard obtains a green card and moves to Florida during the year. In that year Richard is a Category 3 filer, because he became a US person while meeting the 10% stock ownership requirement. For the CFC test, attribution now flows between Richard and his US-citizen children. Richard is deemed to own 30% plus Emma's 15% and James's 5%, a total of 50%, with Margaret's shares still blocked. Emma is deemed to own 15% plus Richard's 30%, or 45%. James is deemed to own 5% plus Richard's 30%, or 35%. All four Americans are now US shareholders, and the shares they actually own total 65%. Hartley Holdings becomes a CFC, all four are Category 5 filers, and James is a US shareholder with only 5% in his name. Richard is also a Category 4 filer, because Margaret's 10% counts toward his control test and takes him to 60%.

Who in the family actually files, and can one Form 5471 cover everyone?

The Form 5471 instructions offer two ways to avoid duplicated returns. The first is the constructive-owner exception for Categories 1, 3, 4 and 5: a filer with no direct interest, caught solely through constructive ownership from another US person, does not file if that person files a Form 5471 reporting all the required information.

The second is the rule for multiple filers of the same information. Where two or more persons must report on the same foreign corporation for the same period, one person with the same or greater filing requirements may file a joint Form 5471 for the others, attached to any one of their tax returns. Everyone named in item H attaches a statement to their own return and, for Category 1a, 1b, 4, 5a or 5b filers, a separate Schedule P. Category 5b and 5c filers cannot file jointly, and a person who lets someone else file can still be penalised if that return is wrong.

Map every shareholder, their relationship to each US family member and their US tax status at every point in the year.
Run the CFC test with section 958(b) rules and the control test with section 6038(e)(2) rules separately.
Identify event-driven Category 2 and Category 3 triggers using the wider section 6046 family definition.
Choose one lead filer with the greatest filing requirements and document the item H statements for everyone else.

How do you get the numbers when non-US relatives control the company?

The hardest part of a family Form 5471 is often the data. A Category 4 filer must report a US dollar balance sheet and income statement, current earnings and profits, and transactions between the company and its shareholders and related parties on Schedule M. When the company is run by British parents or a British spouse who have no US filing obligation of their own, the American relative may have a legal duty to report information they do not control.

The public record helps only partly. Companies House filings can show who holds the shares, and GOV.UK guidance on people with significant control identifies anyone with more than 25% of the shares or voting rights, but share registers say nothing about family relationships or citizenship, and accounts filed by smaller companies often omit the income, balance sheet and related-party detail Form 5471 needs. The practical fix is contractual: a shareholders' agreement clause obliging the company to supply an annual US reporting pack, a standing instruction to the UK accountants to release management accounts, trial balance and related-party schedules after the year end, and written requests kept on file, because a documented effort to obtain information supports a reasonable cause position if a return is late.

What are the Form 5471 penalties and how long does the IRS have to assess?

For a failure to furnish information required by section 6038, which covers Categories 1, 4 and 5, the penalty is $10,000 for each annual accounting period of each foreign corporation. If the failure continues more than 90 days after the IRS mails notice, a further $10,000 applies for each 30-day period or part of one, capped at $50,000 for each failure. A section 6038 failure also cuts the foreign taxes available for credit by 10%, plus 5% for each further three-month period. For Categories 2 and 3, section 6679 imposes $10,000 for each failure for each reportable transaction, with the same $10,000 per 30-day continuation penalty up to $50,000. Criminal penalties under sections 7203, 7206 and 7207 can also apply.

The statute of limitations is the less visible cost. Under section 6501(c)(8), where information required under section 6038 or 6046 has not been furnished, the time for assessing tax on the related return does not expire until three years after the information is provided. An unfiled Form 5471 can therefore leave an otherwise complete US return open indefinitely, with a narrower exposure where the failure is shown to be due to reasonable cause.

How do you fix missed Form 5471 filings in a family company?

The right route depends on whether tax was also underreported and where the family member lives.

Delinquent International Information Return Submission Procedures: for taxpayers not under civil examination or criminal investigation and not contacted by the IRS about the missing returns. The late Form 5471 is attached to an amended return with a reasonable cause statement, though the IRS warns penalties may be assessed before the statement is considered.
Streamlined Foreign Offshore Procedures: for non-willful taxpayers who, as US citizens, had no US abode and were outside the US for at least 330 full days in at least one of the three most recent tax years. They file three years of returns with required information returns such as Form 5471 and Form 8938, six years of FBARs and Form 14653, with no information return or FBAR penalties if eligible.
Streamlined Domestic Offshore Procedures: the equivalent route for non-willful US residents, which carries a miscellaneous offshore penalty.
The IRS withdrew its separate Delinquent FBAR Submission Procedures page in mid-2026, so FBAR gaps now belong inside one of the routes above.

Where the only exposure arose from downward attribution before the 2026 restoration, check the Rev. Proc. 2019-40 relief first, because some of those returns may never have been required. Where a relative was genuinely a US shareholder of a CFC, late Form 5471 filings usually bring subpart F and section 951A calculations, so the income tax return must be corrected too.

How does us-uktax.com handle Form 5471 family attribution?

Our comprehensive US and UK tax preparation and compliance service for family companies starts with a written ownership map of every shareholder, relationship and residence change, then applies the section 958(b), 6038(e)(2) and 6046 rules separately. We coordinate a single lead filer where the instructions allow, prepare item H statements, convert UK accounts into Form 5471 schedules, and prepare late filings and Streamlined submissions where attribution was missed.