Last checked against the official text on 15 October 2026. Authority: Competition and Markets Authority (CMA).
Reference information, not legal advice; confirm with counsel before relying on a figure.
Current thresholds
| Test | Threshold (exceeds) | Applies | Official source | Last checked |
|---|---|---|---|---|
| Turnover in the United Kingdom of the enterprise being taken over Turnover test (Enterprise Act 2002 s 23(1)(b)) |
GBP 100 million | from 1 January 2025 | Enterprise Act 2002, section 23 (legislation.gov.uk) Enterprise Act 2002 s 23(1)(b) |
15 October 2026 |
| Turnover in the United Kingdom of the enterprise being taken over, or of any other enterprise concerned Turnover condition attached to the share of supply test (Enterprise Act 2002 s 23(2)(c)) |
GBP 10 million | from 1 January 2025 | Enterprise Act 2002, section 23 (legislation.gov.uk) Enterprise Act 2002 s 23(2)(c)(i) and (ii) |
15 October 2026 |
| Turnover in the United Kingdom of enterprise E, the enterprise whose existing share of supply is tested Hybrid test, turnover condition (Enterprise Act 2002 s 23(4E)) |
GBP 350 million | from 1 January 2025 | Enterprise Act 2002, section 23 (legislation.gov.uk) Enterprise Act 2002 s 23(4E) |
15 October 2026 |
Who reviews, and is notification mandatory
Mergers in the United Kingdom are reviewed by the Competition and Markets Authority (CMA) under Part 3 of the Enterprise Act 2002. The jurisdictional tests are in section 23, as amended with effect from 1 January 2025 by Schedule 4, paragraph 2 to the Digital Markets, Competition and Consumers Act 2024.
Under section 96 a person authorised by regulations may give the CMA a merger notice; the section uses "may" and imposes no duty to notify. Under section 22 the CMA shall, subject to the exceptions in that section, make a reference to its chair for the constitution of a group where it believes that it is or may be the case that a relevant merger situation has been created and that its creation has resulted, or may be expected to result, in a substantial lessening of competition within any market or markets in the United Kingdom for goods or services; section 22 concerns completed mergers. Under section 72 the CMA may make an order for the purpose of preventing pre-emptive action where it is considering whether to make a reference under section 22, 33, 68B or 68C and has reasonable grounds for suspecting that two or more enterprises have ceased to be distinct, or that arrangements are in progress or in contemplation which would have that result (s 72(1) and (2)). Confirm the position for a specific transaction, including any separate regime that applies by sector or for national security, in the legislation and the CMA's guidance.
The three ways the CMA has jurisdiction in section 23
Each route requires first that two or more enterprises have ceased to be distinct enterprises at a time or in circumstances within section 24. The monetary amounts below are not met by a turnover equal to them: the Act says the turnover "exceeds" the amount, so a turnover equal to the amount does not meet the limb.
Turnover test (s 23(1)). The turnover in the United Kingdom of the enterprise being taken over exceeds GBP 100 million.
Share of supply test (s 23(2) to (4)). As a result of the enterprises ceasing to be distinct, at least one-quarter (25 per cent) of the goods of a description supplied in the United Kingdom, or in a substantial part of it, are supplied by or to one and the same person, or by or to the persons by whom the enterprises concerned are carried on (s 23(3)); section 23(4) states the equivalent for services. The condition must prevail, or prevail to a greater extent, as a result of the merger (s 23(2)(b)). In addition, the United Kingdom turnover of the enterprise being taken over, or of any other enterprise concerned, must exceed GBP 10 million (s 23(2)(c)). Under s 23(2B), turnover of another enterprise concerned that is also turnover of the enterprise being taken over is ignored for the second of those two alternatives. The decision-making authority applies whichever criterion or combination of criteria it considers appropriate to decide whether the proportion is met (s 23(5)).
Hybrid test (s 23(4C) to (4G)). All of the following apply. Were it not for the enterprises ceasing to be distinct, at least 33 per cent of the goods or services of a description supplied in the United Kingdom, or in a substantial part of it, would be supplied by, or to, the person or persons by whom one of the enterprises concerned (E) would be carried on, in the case of supply to them, in connection with E or another enterprise concerned under common ownership or common control with E (s 23(4D)). The United Kingdom turnover of E exceeds GBP 350 million (s 23(4E)). And an enterprise within s 23(4G) (broadly, an enterprise concerned other than E or an enterprise under common ownership or common control with E) satisfies at least one of three connections with the United Kingdom: it would be carried on by a body formed or recognised under the law of any part of the United Kingdom, its activities or part of them would be carried on in the United Kingdom, or the person or persons carrying it on supply goods or services to a person or persons in the United Kingdom in connection with it (s 23(4F) and (4G)). Section 23(4C) to (4G) contains no condition that the enterprises supply goods or services of the same description.
Wording of the Act and of the GOV.UK summary
The three amounts above were inserted or substituted with effect from 1 January 2025: the turnover amount in section 23(1)(b) was substituted by the 2024 Act, and the turnover condition in section 23(2)(c) and the hybrid test in section 23(4C) to (4G) were inserted by it. Section 23(3) and (4), which set the one-quarter share of supply proportion, carry no amendment annotation of their own on legislation.gov.uk. The earlier turnover amount in section 23(1)(b) was lower; this page does not state it.
The Act uses "exceeds" for each of the three monetary amounts. The GOV.UK summary of the tests words the turnover test and the GBP 10 million share of supply condition as "at least" an amount and uses "over" only for the hybrid turnover amount. Where the Act and a summary differ in wording, this page follows the Act.
Changes flagged on the legislation
legislation.gov.uk lists, for the Enterprise Act 2002 as a whole, changes not yet applied to its text, including the insertion of section 58(2EA) and Schedule 8 paragraph 20BB by the Enterprise Act 2002 (Specification of Additional Section 58 Consideration) Order 2026 (S.I. 2026/1075). legislation.gov.uk shows these on the section 23 page as changes yet to be applied, but they insert section 58(2EA) and Schedule 8 paragraph 20BB and do not amend the wording of section 23. The Order came into force on 13 October 2026.
What this page does not cover
This page does not cover when enterprises cease to be distinct (sections 24 to 26), how turnover is calculated and attributed, how a substantial part of the United Kingdom is identified, references in relation to anticipated mergers (section 33), fast-track references (section 22(1A)), public interest and special public interest interventions by the Secretary of State (including the considerations in section 58), the time limits for a reference, the CMA's Phase 1 and Phase 2 timetables, the substantive test and remedies, merger fees, the National Security and Investment Act 2021, sector regimes such as water or media, or the earlier turnover amount. The figures on this page are taken from the Act on legislation.gov.uk; the GOV.UK summary is cited only to compare wording. Confirm procedure and guidance on the CMA's website.
Changes log
- : Page published. Figures checked against the text of section 23 of the Enterprise Act 2002 on legislation.gov.uk.
- : The turnover amount in section 23(1)(b) is substituted, the turnover condition in section 23(2)(c) and the hybrid test in section 23(4C) to (4G) are inserted, by Schedule 4, paragraph 2 to the Digital Markets, Competition and Consumers Act 2024, brought into force on that date by S.I. 2024/1226.
Frequently asked questions
What are the UK merger control jurisdiction thresholds?
Under section 23 of the Enterprise Act 2002 the CMA has jurisdiction where the United Kingdom turnover of the enterprise being taken over exceeds GBP 100 million; or where the merger creates or increases a share of supply of at least one-quarter and the United Kingdom turnover of the target or another enterprise concerned exceeds GBP 10 million; or where one enterprise has a United Kingdom share of supply of at least 33 per cent and United Kingdom turnover above GBP 350 million and another enterprise concerned has a connection with the United Kingdom.
Is UK merger notification mandatory?
Section 96 of the Enterprise Act 2002 provides that a person authorised by regulations may give the CMA a merger notice; the section uses "may" and imposes no duty to do so. Under section 72 the CMA may make an order to prevent pre-emptive action where it is considering whether to make a reference and has reasonable grounds for suspecting that enterprises have ceased, or will cease, to be distinct. Separate regimes outside this page may apply to particular sectors or for national security.
Is a turnover exactly at the threshold enough?
No. Section 23 says the turnover exceeds GBP 100 million (turnover test), exceeds GBP 10 million (share of supply test) or exceeds GBP 350 million (hybrid test), so a turnover equal to the amount does not meet that limb. The share of supply proportions are expressed as at least one-quarter and at least 33 per cent.
Does the hybrid test need the parties to overlap?
Section 23(4C) to (4G) contains no condition that the enterprises supply goods or services of the same description. It requires a 33 per cent share of supply and United Kingdom turnover above GBP 350 million for one enterprise (E), and a connection with the United Kingdom for an enterprise within s 23(4G).