SolvedCTM03940 | Small profits rate: financial year 2023 onwards: associated company definition: introduction
From HM Revenue & Customs · Company Taxation Manual
A company is an associated company of another company if one has control of the other, or both are under the control of the same person or persons. "Control" for this purpose has the same meaning as for close companies (CTA10/PART10, S450 and S451, see CTM60210).
A company may be an associated company regardless of where it is tax resident.
An associated company is counted even if it is an associated company for only part of an accounting period (but see CTM03955 where the accounting period straddles 2 financial years where there is a change in the upper or lower limits or fractions).
An associated company which has not carried on any trade or business (see CTM03945) at any time during the accounting period is disregarded. If that company is an associated company for only part of the accounting period and has not carried on any trade or business at any time during that part of the accounting period, it is also disregarded.