Building a High-Performing In-House Tax Function in the UK

30 April 2026

The Expanding Mandate of the Head of Tax

The role of Head of Tax in the UK has fundamentally evolved. No longer defined by compliance alone, tax leaders are now expected to demonstrate control, align closely with business strategy, and navigate an increasingly complex and scrutinised regulatory environment (HMRC, OECD BEPS framework).

This shift is not incremental, it requires a rethinking of how tax functions are designed, resourced and operated.

Operating Model: Establishing Control and Clarity

At the core of high-performing tax teams is a well-defined operating model.

Leading functions are built on clear ownership of responsibilities, structured processes, and embedded controls across the full tax lifecycle. They move away from reactive, fragmented approaches towards models where accountability and review are integrated into day-to-day activity.

This level of structure is increasingly expected as part of good tax governance and risk management (ICAEW). It provides the foundation for consistency, reduces key-person dependency, and enables the function to operate with confidence under scrutiny.

Capability: Broadening the Skillset

However, structure alone does not deliver performance.

The role of the in-house tax professional is evolving. While technical expertise remains essential, it now needs to be complemented by broader skills, particularly in communication, data, and technology, with AI becoming a key part of the upskilling process.

Tax teams are also expected to engage more directly with stakeholders across finance, legal and the wider business. This requires the ability to translate complex tax issues into clear, commercially relevant insight that supports decision-making.

The most effective teams combine technical depth with strong communication and practical delivery capability, reflecting wider expectations across the UK profession (CIOT).

Governance: Demonstrating Control in Practice

As expectations increase, governance has become a central focus.

Tax functions must be able to clearly demonstrate how risks are identified, managed and monitored. This goes beyond having policies in place. It requires clear process ownership, defined review frameworks, and consistent, auditable evidence of control effectiveness.

Frameworks such as the UK Corporate Governance Code reinforce the importance of robust internal controls and transparency (FRC).When implemented effectively, governance becomes an enabler, providing clarity and assurance to both internal and external stakeholders.

Technology: Responding to International Tax Complexity

Technology is now critical, but its role is most visible in managing increasing international tax complexity.

The introduction of global minimum tax rules under Pillar Two is a clear example. These rules introduce significant new data, calculation and reporting requirements for multinational groups, requiring tax functions to access, standardise and analyse data across multiple jurisdictions (OECD Pillar Two).

For many in-house teams, this represents a step change.

Legacy processes, often reliant on spreadsheets and manual consolidation, are no longer sufficient. Leading organisations are investing in technology and data infrastructure to:

  • Aggregate and standardise tax and financial data across entities
  • Automate complex calculations and reporting requirements
  • Maintain audit trails and support governance obligations

This is not simply about efficiency. It is about enabling compliance at scale while maintaining control and reducing risk.

More broadly, international tax developments are accelerating the need for system-led approaches. Without this, the operational burden on tax teams becomes unsustainable.

Scalability: Designing for Change

As complexity continues to increase, scalability becomes a defining characteristic of high-performing teams.

This is not about increasing workload, but about building an operating model that can flex without compromising control. In practice, this often involves a combination of internal capability, selective external support, and clear documentation to reduce reliance on individual expertise.

With ongoing developments in international tax (OECD), the ability to scale effectively is becoming essential.

People: Sustaining Long-Term Performance

Ultimately, performance is driven by people.

Attracting and retaining talent remains a significant challenge for in-house tax functions. The most effective teams invest in development, create clear progression pathways, and foster collaborative environments where knowledge is shared.

Expectations have shifted. Flexible working, modern tools and meaningful work are now baseline requirements rather than differentiators (ACCA). Teams that fail to address this risk losing capability at a critical time.

Conclusion: Performance is a Matter of Design

Building a high-performing in-house tax function is not a question of size, it is a question of design.

A clear operating model, supported by the right capabilities, governance and technology, enables tax teams to move beyond compliance and operate as confident, trusted partners to the business.

In a landscape defined by international complexity and regulatory change, that is what separates leading tax functions from the rest.

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