The UK Finance Bill 2025-26 introduces a package of measures that will significantly reshape the regulatory landscape for tax advisers. From mandatory registration requirements to expanded grounds for sanctions and a new strict liability criminal offence, these provisions represent a fundamental shift in how HMRC oversees and enforces standards within the profession.
The Institute of Chartered Accountants in England and Wales (ICAEW) has raised substantial concerns about the breadth of these measures and their potential to penalise legitimate professional judgement rather than genuine misconduct. For practitioners, understanding these changes is essential. The consequences of non-compliance range from financial penalties and suspension of practice rights through to criminal prosecution under the UK Finance Bill.
This briefing examines each of the three key measures in turn, sets out the practical implications for advisory firms, and summarises the profession’s response to what many consider the most significant regulatory intervention in a generation concerning the UK Finance Bill.
Overview of the UK Finance Bill
- From May 2026, all UK tax advisers communicating with HMRC must register and can face up to 12 months suspension if their behaviour falls below expected standards.
- The threshold for sanctions drops from “dishonest conduct” to “sanctionable conduct,” meaning advisers can be penalised simply for intending to reduce tax liability, even in good faith disputes.
- A new strict liability criminal offence will prosecute advisers for promoting arrangements with no realistic prospect of success, regardless of intent or honest belief.
- ICAEW warns these measures could force mainstream advisers out of complex tax work, paradoxically weakening compliance as clients turn to unqualified advisers or proceed without professional guidance.
- A single mistake could trigger all three consequences simultaneously: criminal prosecution, financial penalties up to £1 million, and loss of registration that destroys client relationships and threatens firm survival.
The Three New Regulatory Threats
The UK Finance Bill 2025-26 introduces three interconnected measures that ICAEW warns could fundamentally damage the tax advisory profession and harm compliant taxpayers.
Mandatory Agent Registration (May 2026)
As we approach the UK Finance Bill implementation date, it is crucial for all tax advisers to be fully aware of these changes.
Starting May 2026, every tax adviser who communicates with HMRC on behalf of clients must register. To register, advisers must meet strict minimum standards. Their firm and key staff must be up to date with their own tax affairs and cannot have received an anti-avoidance penalty in the past 12 months.
The critical problem is what happens next. HMRC can suspend registration for up to 12 months if it believes the adviser’s behaviour “falls below the standards that might reasonably be expected.” For many firms, losing registration is an existential threat. They cannot act for any clients during suspension, which could destroy thousands of client relationships and put firms out of business entirely.
ICAEW’s concerns are specific and serious. First, there is no explicit test requiring HMRC to act proportionately or reasonably before imposing suspension. Second, HMRC officers are not bound by HMRC’s own standards when judging advisers. Third, the regime has retrospective effect. A historic mistake that cannot be fixed could disqualify a firm permanently. For example, if a firm missed a disclosure requirement under the DOTAS regime years ago and received a penalty, that penalty could still prevent registration today, even if the firm has been fully compliant since.
Additionally, ICAEW notes the real wrongdoers will not be caught. Only advisers who interact directly with HMRC must register. Rogue operators who work entirely outside the HMRC system face no registration requirement at all.
The UK Finance Bill mandates that tax advisers adhere strictly to new registration protocols to maintain compliance.
Lowered Threshold for Sanctionable Conduct (April 2026)
Currently, HMRC can only penalise tax advisers for dishonest conduct. The new law changes “dishonest conduct” to “sanctionable conduct,” defined as acting “with the intention of bringing about a loss of tax revenue.”
This is a dramatic lowering of the bar. The current test requires dishonesty. The new test only requires intention to cause revenue loss. This distinction is crucial.
ICAEW’s objection is forceful and well-founded. The new definition could catch legitimate professional disagreements. Imagine a tax adviser and HMRC both interpret complex legislation differently, both acting in good faith. If HMRC believes the adviser intended (even indirectly) to help the client save tax, sanctions could follow. Every tax return entry and every piece of advice would theoretically need to be assessed against future HMRC challenge risk.
Consider a technical dispute over how anti-avoidance rules apply to a complex transaction. The adviser gives advice based on their interpretation of the law. HMRC disagrees. Under the old law, the adviser would not be penalised unless they acted dishonestly. Under the new law, if HMRC can argue the adviser intended to bring about tax loss, penalties apply. The intention element is broadly interpreted.
Penalties are capped at £1 million for the first breach, calculated by reference to potential lost revenue. This is significant financial exposure.
ICAEW warns this will drive mainstream advisers out of complex or higher-risk work entirely. Paradoxically, this weakens tax compliance rather than strengthens it. When experienced advisers retreat, clients either get no advice, rely on unqualified advisers, or take aggressive positions without professional input.
The implications of the UK Finance Bill will be felt across the industry, as advisers navigate the new standards set forth.
New Criminal Offence (Two Months After Royal Assent)
With the UK Finance Bill in place, the landscape of tax advisory work is set to change dramatically.
The Bill creates a strict liability criminal offence for promoting arrangements with “no realistic prospect” of delivering a tax advantage. Strict liability means intent is irrelevant. You can be prosecuted even if you genuinely believed the arrangement would work.
This is extraordinarily broad. Tax advice is complex and fact sensitive. Mistakes happen routinely from overlooking anti-avoidance provisions, receiving incomplete client information, or misunderstanding developing case law. Currently, these issues are addressed through professional standards, civil penalties and negligence claims. The profession has existing accountability mechanisms.
Criminalising honest mistakes is disproportionate, ICAEW argues. And the criminal penalties compound the registration problem. A criminal conviction (or even prosecution) could trigger loss of registration simultaneously, creating cascading professional destruction.
Why ICAEW Is Alarmed?
The three measures in the UK Finance Bil work together to create a pincer movement against the profession. Registration suspension threatens business continuity. Sanctionable conduct penalties are almost impossible to avoid in complex cases. Criminal liability makes honest mistakes potentially criminal. A single mistake could trigger all three consequences.
The unspoken concern is that this creates a chilling effect. Advisers become so afraid of crossing undefined lines that they withdraw from legitimate advisory work. Clients either pay more for excessive caution or make tax decisions without proper professional guidance.
The three measures encapsulated in the UK Finance Bill create a challenging environment for advisers.
ICAEW's Specific Demands
ICAEW’s demands reflect the urgent need for clarity within the framework of the UK Finance Bill.
ICAEW has asked for three things:
- First, limit sanctions to genuinely unethical or unreasonable conduct. Restore a reasonableness requirement.
- Second, ensure criminal offences target actual wrongdoing, not honest mistakes.
- Third, protect legitimate professional judgement from triggering sanctions.
Additionally, ICAEW wants implementation delayed until 2027 at the earliest, with proper consultation and impact assessment.
Historical Context
In July 2025, the government published draft legislation requiring all partners in a firm to register, regardless of whether they worked in tax. ICAEW successfully campaigned against this. The current version requires only relevant individuals (roughly five per firm with six or more partners) to register. This is a partial victory, but the core problems remain.
At the Autumn Budget 2025, the government said it would not regulate advisers. Yet this Bill does precisely that. ICAEW’s frustration is understandable.
Historical context surrounding the UK Finance Bill reveals the evolution of regulatory practices in tax advisory.
Helpful Resources
- UK Tax Advisers Face Mandatory HMRC Registration from May 2026: Tax Advisers Face Mandatory HMRC Registration I FigsFlow
- List of AML Regulations & Regulators in the UK: List of UK AML Regulations for Accountants 2025 | FigsFlow
- Discover the Best AML Tools for Tax Advisers: Anti-Money Laundering Compliance Tools for Tax Advisers | FigsFlow
- HMRC is Targeting “Unethical” Tax Advisers: Rogue Tax Advisers Beware: HMRC is coming for you!
- Everything You Need to Know About Form-8 Formal Authorisation to Act as a Tax Agent: Form 64-8: Tax Agent Authorisation Guide for Accountants | FigsFlow
- Complete AML Guidance for Tax Advisers: Anti-Money Laundering Guidance for Tax Advisers: A Complete Guide
Conclusion
These measures in the UK Finance Bill 2025-26 are genuinely threatening to the UK tax advisory profession. They shift enforcement toward the profession rather than toward tax avoidance schemes themselves. They create incentives for advisers to over-comply at the expense of legitimate tax planning. They may inadvertently strengthen the market position of unscrupulous operators who operate entirely off HMRC’s radar.
The core problem is that all three measures are broadly drafted with insufficient safeguards for ordinary professional practice. They conflate genuine wrongdoing with technical disagreement. This is why ICAEW has described them as posing existential risk to mainstream firms.
