A second company can look like a smart way to separate risk, brands, or business activities. However, it can also quietly change your Corporation Tax position.
The Associated Companies rules can reduce key tax thresholds simply because another company sits under common control. That can increase Corporation Tax and bring payment dates forward, even when profits stay the same.
The problem is that many directors only discover this after the structure is already in place. By then, the tax impact may already affect marginal relief, cash flow, and year-end planning.
So, before forming another company, buying a business, or restructuring ownership, it is worth asking one important question: could HMRC treat these companies as associated?
Key Takeaways
- Associated companies can reduce the £50,000 and £250,000 Corporation Tax thresholds.
- Family-owned companies can become associated in some circumstances, particularly where their businesses are commercially interdependent.
- An associated company can count even if the connection existed for only part of the accounting period.
- The rule can also bring forward Corporation Tax payments under the quarterly instalment regime.
What Are Associated Companies?
Under the Corporation Tax rules, companies are generally associated where one company controls the other, or both are controlled by the same person or persons. HMRC applies the close-company control tests when assessing this relationship. A company can count even when it is resident outside the UK.
Owning more than 50% of a company’s ordinary shares often creates control. However, HMRC looks beyond simple share ownership. Control can arise through:
• voting power
• share capital ownership
• rights to company income
• rights to assets on winding-up
• powers contained within company agreements
It can also consider direct or indirect control over the company’s affairs. This wider test often catches structures that look separate on a Companies House search.
A group of people can control a company together. Therefore, accountants should review shareholder combinations, articles, shareholder agreements, and unusual rights. They should not rely only on the percentage shown beside each shareholder’s name.
How Associated Companies Change Tax
For standard non-ring-fenced companies, the main Corporation Tax rate is 25%. The small profits rate is 19%.
The standard profit thresholds are:
|
Corporation Tax position |
Standard limit |
|
Small profits rate |
Up to £50,000 |
|
Marginal Relief range |
£50,001 to £250,000 |
|
Main rate |
Above £250,000 |
These limits apply before adjusting for associated companies and short accounting periods.
Associated companies divide those limits by the total number of companies in the calculation. That total includes the company itself. One associated company therefore halves both limits. Three associated companies create four companies for the threshold calculation.
|
Companies in calculation |
Lower limit |
Upper limit |
|
1 |
£50,000 |
£250,000 |
|
2 |
£25,000 |
£125,000 |
|
3 |
Approx. £16,667 |
Approx. £83,333 |
|
4 |
£12,500 |
£62,500 |
Short accounting periods further reduce the limits. HMRC requires a time-based adjustment for periods shorter than twelve months. Directors should, therefore, check both company count and accounting-period length before estimating Corporation Tax.
The test uses augmented profits, not simply the profit shown in statutory accounts. Augmented profits broadly include taxable total profits and certain exempt distributions received from other companies. This distinction can affect whether the company reaches the reduced limits.
(Source: Corporation Tax rates and allowances – GOV.UK)
A Simple Example
Assume a company has £60,000 of augmented profits and no associated companies. Its profits fall within the standard marginal relief range.
If the owner also controls another active company, the Corporation Tax limits reduce to £25,000 and £125,000 because two companies are included in the calculation.
The first company’s underlying profit has not changed. However, its Corporation Tax position has changed because the second company reduces the available thresholds. This is why directors should review the tax impact before forming another company.
Family Companies Need Care
A spouse’s company does not automatically become associated with yours. However, HMRC can attribute rights held by certain associates where the statutory conditions apply. This is particularly relevant where companies have substantial commercial interdependence.
HMRC considers three main forms of connection.
Financial links
A financial link may exist where one company financially supports another.
Examples include:
• intercompany loans
• guarantees
• shared finance arrangements
• one business depending financially on another
Economic links
Businesses may have economic links where they support the same commercial activity.
This could include businesses that:
• serve similar customers
• provide complementary services
• operate within the same supply chain
• depend on each other’s business activity
Organisational links
Organisational links can arise where companies share business resources.
Examples include shared:
• directors or managers
• employees
• premises
• equipment
• administrative systems
One connection alone does not always mean the companies are associated. HMRC considers the overall commercial relationship.
Companies Directors Often Overlook
Owners commonly remember their main trading companies but overlook other entities. This can produce an incorrect Corporation Tax computation. Accountants normally review the whole ownership picture before finalising the CT600.
Common examples include:
• overseas companies
• newly acquired businesses
• holding companies
• companies owned jointly with another person
• companies controlled through unusual voting rights.
A company associated for only part of an accounting period can still count.
HMRC disregards an associated company if it carried on no trade or business during the relevant period. Certain passive holding companies can also fall within a specific exclusion. The company’s actual activities should therefore be checked before excluding it.
Quarterly Payments Can Start Earlier
The associated companies rule also affects Corporation Tax payment timing. Large companies normally enter quarterly instalment payments above an annual profit threshold of £1.5 million. For periods beginning on or after 1 April 2023, associated companies divide that threshold.
Suppose a company has five associated companies. The £1.5 million threshold becomes £250,000 because six companies enter the calculation. A company earning £300,000 could therefore fall within the quarterly instalment regime. However, specific exceptions and transitional rules may apply. The position should be checked before assuming quarterly payments are required.
The quarterly payment rules contain further exceptions and timing conditions. These should be reviewed before assuming instalments apply. Some instalments can become due before the accounting period ends.
This timing difference can create cash flow pressure. Growing groups should forecast Corporation Tax alongside other major payments.
(Source: Pay Corporation Tax if you’re a large company)
Filing and Compliance Points
The CT600 includes specific fields for associated companies. Boxes 326 to 328 record associated company information for the relevant period and financial years. Directors should therefore confirm the ownership structure before the return is finalised.
Most companies pay Corporation Tax nine months and one day after their accounting period ends. The Corporation Tax return normally falls due twelve months after that period ends. Quarterly instalment payers follow different payment rules.
There is no separate fixed penalty simply for having associated companies. However, an incorrect count can understate tax. HMRC can charge interest and penalties where tax is understated, depending on the circumstances.
Common Mistakes
Several mistakes regularly appear when directors operate more than one company:
• checking only ordinary share percentages
• ignoring voting rights or shareholder agreements
• assuming different trades cannot be associated
• forgetting overseas or recently acquired companies
• treating every dormant company as automatically excluded
• assuming a spouse’s company always counts
• confusing Corporation Tax associations with VAT rules
The final point deserves particular attention. The Corporation Tax association does not determine VAT registration. VAT grouping and artificial separation use different tests. The guide to VAT disaggregation between connected companies explains that distinction in more detail.
What Directors Should Check
Before forming, buying, or restructuring another company, map every company connected to the owners. Record share percentages, voting rights, dividend rights, and rights on a winding-up. Include relevant overseas companies and family-controlled companies.
Next, identify financial, economic, or organisational links between family-owned businesses. Review loans, shared staff, premises, customers, and management arrangements. Then calculate each company’s adjusted Corporation Tax thresholds.
Your accountant should also review augmented profits and quarterly instalment thresholds before year-end. Current figures give directors time to plan cash flow and payment dates.
Accurate bookkeeping services can make this review easier by keeping intercompany balances and transactions clearly recorded.
Conclusion
Associated Companies rules can change both Corporation Tax rates and payment timing across connected businesses. The risk often appears after a second company starts trading. Directors should review control, family links, company activity, and adjusted thresholds before each year-end.
If your ownership structure has changed, review the position before filing the CT600. Professional advice can help confirm the correct thresholds and identify any earlier payment obligations.
