HM Revenue & Customs (HMRC) has updated its formal guidance today, 29 September 2026, regarding compliance checks for the UK’s largest and most complex business organisations.
The refreshed factsheet, known as CC/FS1c, provides the latest procedural framework for how the tax authority monitors and audits businesses managed by its Large Business and Mid-sized Business directorates.
The Large Business Directorate (LBD) works with approximately 2,000 of the UK’s largest and most complex businesses.
According to HMRC data, these large businesses, along with their employees and customers, account for roughly 40% of the total tax revenue collected in the UK.
The role of the Customer Compliance Manager
A central feature of the relationship between HMRC and these major organisations is the Customer Compliance Manager (CCM). A CCM is a senior professional assigned to each of the UK’s largest businesses as a primary point of contact.
When a compliance check is initiated, the CCM or a dedicated case officer will lead the process, which may involve reviewing records, visiting business premises, or requesting digital data.
Outcomes and Penalties
The updated guidance clarifies the three potential outcomes of any compliance check:
- No change: The check confirms the tax affairs are correct.
- Refund: HMRC identifies that the business has overpaid and arranges a repayment.
- Additional tax: The check reveals an underpayment. In these cases, the business must pay the outstanding amount plus interest and may face financial penalties.
Businesses maintain the right to represent themselves or appoint an authorised agent, such as an accountant or legal professional, to handle the proceedings on their behalf.
2026 Regulatory Context
The update to factsheet CC/FS1c arrives at a time of increased technical scrutiny.