Deals in the United States are shaped by three federal filters: Hart-Scott-Rodino merger notification to the FTC and DOJ, national security review by CFIUS for foreign buyers, and, for US investors going outward, Treasury's outbound investment rules. Company law, takeovers of private companies and most deal mechanics are governed by the law of the state of incorporation, so federal clearances sit on top of state-law processes.
Merger control: Hart-Scott-Rodino
Acquisitions above the 2026 size-of-transaction threshold of 133.9 million US dollars may need notification to the Federal Trade Commission and the Department of Justice Antitrust Division before closing. Between 133.9 million and 535.5 million US dollars a size-of-person test also applies; above 535.5 million US dollars the deal is reportable whatever the size of the parties, subject to exemptions. Filing fees rise in six tiers from 35,000 to 2,460,000 US dollars.
Closing must wait until the waiting period ends, normally 30 days (15 for a cash tender offer). Closing early, known as gun-jumping, exposes the parties and their officers to daily civil penalties. The expanded notification form introduced in February 2025 was vacated by a federal court; since 19 March 2026 parties may use the earlier form, although the FTC has appealed.123456
CFIUS national security review
CFIUS can review foreign investments in US businesses and certain real estate deals. Most filings are voluntary, but a declaration is mandatory at least 30 days before closing where a foreign government-linked investor acquires a substantial interest in a TID US business (critical technology, critical infrastructure or sensitive personal data), or where the target deals in export-controlled critical technologies. CFIUS has 30 days to assess a declaration; a full notice gets a 45-day review that can lead to an investigation.
Foreign buyers should build the CFIUS analysis into the deal timetable and the risk allocation in the purchase agreement, including for voluntary filings. Treasury is piloting a Known Investor Program for repeat investors from allied countries, but this does not change the legal tests. Investors from excepted foreign states, which include the United Kingdom and New Zealand, can benefit from narrower jurisdiction if they meet the qualifying conditions.7891011
Outbound investment rules
Since 2 January 2025 US persons, including US subsidiaries of foreign groups, must notify Treasury of, or must not make, certain investments in Chinese (including Hong Kong and Macau) entities active in semiconductors, quantum technologies and artificial intelligence. Buyers acquiring a US company should check whether the target has made such investments, and US investment vehicles should screen targets before committing.12
| Item | 2026 figure |
|---|---|
| Size-of-transaction threshold | 133.9 million US dollars |
| Size-of-person test applies up to | 535.5 million US dollars |
| Size-of-person test | 267.8 million and 26.8 million US dollars |
| Fee: below 189.6 million US dollars | 35,000 US dollars |
| Fee: 189.6 million to below 586.9 million | 110,000 US dollars |
| Fee: 586.9 million to below 1.174 billion | 275,000 US dollars |
| Fee: 1.174 billion to below 2.347 billion | 440,000 US dollars |
| Fee: 2.347 billion to below 5.869 billion | 875,000 US dollars |
| Fee: 5.869 billion or more | 2,460,000 US dollars |
How it works, step by step
- Test the deal against the 2026 HSR thresholds and exemptions12Federal Trade Commission Premerger Notification Office
- File HSR notifications and pay the fee; observe the waiting period before closing34Federal Trade Commission and Department of Justice Antitrust Division
- Assess CFIUS jurisdiction and whether a mandatory declaration is required; file at least 30 days before closing if so7Committee on Foreign Investment in the United States (chaired by Treasury)
- Respond to the CFIUS assessment or review and negotiate any mitigation89CFIUS
No timings or fees are shown unless an official source states them.
Documents usually needed
- HSR notification form, transaction documents and the competition-related documents required with the form
- CFIUS declaration or notice with ownership chart showing foreign government interests
- Export classification analysis of the target's technologies
- Outbound investment diligence on the target's holdings in countries of concern
- Purchase agreement conditions and risk allocation for HSR and CFIUS clearance
Common mistakes
- Using last year's HSR thresholds; they are revised every year and the 2026 figures applied from February 2026.
- Integrating businesses or exercising control before the HSR waiting period ends.
- Assuming CFIUS applies only to control deals; minority investments with certain rights in TID US businesses can be covered.
- Missing a mandatory CFIUS declaration because the critical technology export analysis was not done.
- Overlooking outbound investment rules when a US target has Chinese portfolio holdings in covered sectors.
When the business crosses borders
- Foreign-to-foreign deals can still require HSR filing where the target has sufficient US assets or sales, subject to foreign-transaction exemptions.
- CFIUS treats qualifying investors from excepted foreign states, which include the United Kingdom and New Zealand, more favourably, but control transactions remain reviewable.
- Outbound investment rules apply to US subsidiaries of foreign groups, which can affect group-wide China investment plans.
Questions businesses ask
What is the HSR threshold in 2026?
133.9 million US dollars for the size-of-transaction test, with a size-of-person test for deals up to 535.5 million US dollars.12
Is a CFIUS filing compulsory?
Only in defined cases: foreign government-linked investors taking a substantial interest in a TID US business, and deals involving export-controlled critical technologies. Otherwise filing is voluntary, and parties decide whether to file based on the national security profile of the deal.7
What this guide does not yet confirm
These points need checking with a qualified local professional in the United States before you rely on them.
- The FTC's own HSR thresholds page could not yet be checked; figures were confirmed on the Federal Register notice instead.
- The outcome of the FTC's appeal against vacatur of the expanded HSR form after March 2026 was not confirmed.
- The current inflation-adjusted HSR daily civil penalty was not confirmed.
- CFIUS investigation-phase length, filing fees and real estate rules were not source-checked.
- Securities law (tender offers, beneficial ownership reporting) and state corporate law, including Delaware, were not researched.
- Federal bankruptcy law, including Chapter 11 and Chapter 15 for cross-border insolvency, was not source-checked.
- Whether the outbound investment programme has been codified or expanded by legislation was not confirmed.
Sources and review status
Each statement is numbered to the source it was checked against. We use official sources where we can, and each statement says whether it was checked against an official or a secondary source. Sources last checked on 19 October 2026. None of it has been professionally reviewed yet: it is research checked against official and secondary sources by WONE Global, not legal or tax advice.
For 2026 the Hart-Scott-Rodino size-of-transaction threshold is 133.9 million US dollars. Federal. Applies to acquisitions of voting securities, non-corporate interests or assets. Exemptions apply. The 2026 figures took effect 30 days after publication in the Federal Register on 16 January 2026.
The notice states it takes effect 30 days after publication; the 17 February 2026 effective date is reported by secondary sources (e.g. Covington & Burling, January 2026) because the thirtieth day fell on a weekend and a public holiday. The FTC's own current-thresholds page could not yet be checked.
For 2026, transactions valued above 133.9 million but at or below 535.5 million US dollars are reportable under HSR only if one party has at least 267.8 million and the other at least 26.8 million US dollars in annual net sales or total assets; transactions above 535.5 million US dollars are reportable regardless of party size. Federal. Subject to HSR exemptions, including for certain foreign transactions.
2026 HSR filing fees range from 35,000 US dollars for transactions below 189.6 million US dollars to 2,460,000 US dollars for transactions of 5.869 billion US dollars or more. Federal. Six fee tiers; the acquiring person normally pays.
Who pays the fee is not stated in the notice read.
After both parties file an HSR notification, they may not close until a waiting period ends, normally 30 days, or 15 days for a cash tender offer, unless extended by a second request or terminated early. Federal; applies to the FTC and DOJ Antitrust Division.
Statutory text read on the Cornell Legal Information Institute reproduction of the United States Code; the official text is published at uscode.house.gov.
Failure to comply with the HSR Act exposes a person, and its officers, directors or partners, to a civil penalty set by statute at up to 10,000 US dollars for each day of non-compliance. Federal. The daily maximum is adjusted annually for inflation; the current adjusted figure was not confirmed.
Statutory text read on the Cornell Legal Information Institute reproduction of the United States Code; the official text is published at uscode.house.gov. The inflation-adjusted daily maximum is materially higher than the statutory 10,000 US dollars.
A federal district court vacated the expanded HSR notification rules that had applied since February 2025, and after the Fifth Circuit denied a stay on 19 March 2026 parties may file using the earlier HSR form; the FTC has appealed and said it will still accept the newer form. Federal. The FTC may still seek additional information through voluntary access letters and second requests. Status depends on the outcome of the appeal.
Law firm alert used because the FTC page could not yet be checked. The appeal outcome after March 2026 was not confirmed.
A declaration to CFIUS is mandatory, at least 30 days before completion, where a foreign person acquires a substantial interest in a TID US business and a single foreign government has a substantial interest in that foreign person, or where a TID US business deals in critical technologies that would need a US export authorisation for the relevant foreign investors. Federal (31 CFR Part 800). TID means critical technology, critical infrastructure or sensitive personal data businesses. Exceptions include excepted investors and certain US-managed funds. A full notice may be filed instead of a declaration.
The eCFR is an authoritative but unofficial editorial compilation; the official text is the annual CFR edition and Federal Register.
CFIUS must complete its assessment of a declaration within 30 days of receiving it. Federal. At the end CFIUS may clear the transaction, request a notice, or state it cannot conclude action.
Regulatory text read on the Cornell Legal Information Institute reproduction of the Code of Federal Regulations; the eCFR at ecfr.gov is the government version. Possible outcomes are general knowledge, not quoted from the page.
CFIUS reviews a full written notice in a 45-day period starting when the notice is accepted, which may be followed by an investigation. Federal. The investigation phase length (45 days, extendable) was not confirmed on the page read.
Regulatory text read on the Cornell Legal Information Institute reproduction of the Code of Federal Regulations; the eCFR at ecfr.gov is the government version.
Treasury is running a pilot Known Investor Program that collects information from eligible foreign investors before a CFIUS filing, and does not change CFIUS jurisdiction or the review process. Federal. Treasury issued a request for information on the programme and on streamlining reviews on 6 February 2026; comments closed on 18 March 2026.
In January 2023 Treasury determined that New Zealand and the United Kingdom meet the requirements to be excepted foreign states and excepted real estate foreign states for CFIUS purposes. Federal. Excepted status can relieve qualifying investors from mandatory declarations and certain non-controlling investment and real estate jurisdiction; control transactions remain reviewable.
The effect of excepted status in the scope field is general knowledge of 31 CFR Parts 800 and 802, not stated on the page read. Australia and Canada have also been excepted foreign states; not confirmed on the page read.
Since 2 January 2025 Treasury's Outbound Investment Security Program prohibits, or requires notification of, certain investments by US persons in entities linked to China (including Hong Kong and Macau) active in semiconductors and microelectronics, quantum information technologies or artificial intelligence. Federal (31 CFR Part 850). Applies to US persons investing outward, including US subsidiaries of foreign groups. Notifications are filed through the Outbound Notification System.
Whether later legislation codified or expanded this programme was not confirmed.
Questions on this topic
12 statements on m&a, merger control, foreign investment screening and restructuring in the United States
