CASS 6 Audit Firms UK: Top Providers and Services Guide

Choosing a CASS 6 audit provider is not just a routine compliance task for FCA-regulated firms. It can affect how clearly a business understands its custody asset arrangements, how well it manages control processes, and how prepared it feels when reporting obligations come around.

Across the UK, firms may work with different types of audit providers, from larger accountancy networks with financial services teams to specialist practices focused on regulated businesses. Each provider may bring a different level of CASS knowledge, sector experience, reporting style, and practical understanding of client asset rules.

This guide highlights a selection of CASS 6 audit companies operating in the UK. It is not intended as a strict ranking. The aim is to give useful context – who these firms are, what types of regulated businesses they usually support, and where their CASS 6 audit services may be most relevant.

Acumon

Acumon is a UK firm of chartered accountants and registered auditors supporting companies, charities, regulated organisations, and international corporate groups with audit and assurance services.

The firm works with a broad range of organisations, from growing owner-managed businesses and charities through to larger groups and regulated entities. Its audit work is carried out in line with International Standards on Auditing (UK), using a structured, risk-focused approach that helps identify the areas most relevant to each engagement.

For FCA-regulated firms, CASS 6 audits focus on the systems, controls, records, and governance arrangements used to protect custody assets. These audits are particularly relevant for firms that hold, safeguard, or arrange custody of client assets under the FCA Client Assets Sourcebook. A CASS 6 audit helps assess whether a firm’s processes are properly designed, documented, and operated in line with the relevant custody rules.

Acumon also holds a Public Interest Entity (PIE) audit licence, which allows the firm to audit listed companies and other organisations that fall under enhanced regulatory oversight in the UK. PIE audit work is subject to additional quality, independence, and regulatory supervision requirements, and only a restricted number of audit firms are authorised to carry out this type of engagement.

Alongside its UK audit registration, Acumon holds audit licences in several international financial centres, including the Cayman Islands, British Virgin Islands (BVI), Jersey, and Isle of Man. This allows the firm to support corporate groups with entities across more than one jurisdiction.

International group structures often include UK operating companies, offshore holding entities, investment vehicles, and regulated entities. These structures are common in areas such as investment management, technology, energy, and international trade. Coordinating audit work across them requires an understanding of cross-border reporting, group consolidation, regulatory expectations, and the way controls operate across different parts of a group.

Acumon works with finance teams, boards, and regulated firms to support statutory audit, CASS-related audit requirements, governance reviews, and stronger financial reporting controls as organisations grow or become more complex.

Audit Capabilities

Acumon provides audit and due diligence services across a wide range of organisational structures and sectors. 

These include:

• UK limited companies and corporate groups
• Public Interest Entities (PIEs) and regulated organisations
• UK subsidiaries of international groups
• charities and not-for-profit organisations
• owner-managed businesses approaching statutory audit thresholds
• offshore holding companies and investment vehicles

Audit and due diligence engagements are typically led by senior audit professionals who remain directly involved throughout the work. This helps ensure that key reporting, regulatory, and control matters are reviewed with the right level of oversight.

Regulatory Licences and Registrations

Acumon holds several audit registrations that allow it to support organisations with UK and international audit requirements, including groups with entities in regulated and offshore financial centres.

These include:

• UK statutory audit registration
• Public Interest Entity (PIE) audit licence
• Jersey audit licence
• Isle of Man audit licence
• Cayman Islands audit licence
• British Virgin Islands audit licence

These registrations enable the firm to provide audit services to groups that include entities in both the UK and key international financial centres.

Core Services

In addition to statutory external audit, Acumon provides services that support financial reporting, governance, compliance, and risk oversight. 

These include:

• statutory external audit
• group and subsidiary audits
• Public Interest Entity (PIE) audits
• charity and not-for-profit audit
• audit of international group structures
• internal audit and governance reviews
• risk management and compliance support

Audit work is often delivered alongside practical discussions with management and boards about financial reporting processes, governance frameworks, and the controls needed to support regulatory obligations.

Many organisations first engage with audit requirements as they grow, enter regulated markets, expand internationally, or exceed the audit exemption thresholds set out in the Companies Act. FCA-regulated firms may also need specialist audit input where custody asset arrangements, client asset controls, and CASS reporting obligations apply.

Acumon works with businesses that are:

• approaching their first statutory audit
• preparing for external investment
• expanding into international markets
• operating within corporate group structures

Early engagement with an audit firm can help ensure that financial reporting systems, governance records, custody asset documentation, and control processes are properly prepared before audit or regulatory review.

Contact Information

• Website: acumon.com
• Phone: 020 8567 3451
• E-mail: mail@acumon.com
• Address: 1-2 Craven Road, Ealing, London, W5 2UA, UK

BKL

BKL provides specialized regulatory assurance services to firms handling client assets under the Financial Conduct Authority (FCA) framework. Their approach involves analyzing a business’s operational model to identify risk areas, ensure strict adherence to deadlines, and recommend adjustments to internal management systems. By coordinating these reviews alongside routine financial reporting, they aim to minimize organizational downtime during the evaluation process.

The team works alongside external legal and regulatory consultants to support financial technology startups and established businesses as they scale. They also assist financial services firms in adjusting to newer regulatory expansions, such as updated safeguarding mandates for electronic money institutions, applying past experience with regulated structures to manage compliance obligations.

Key Highlights

• Work with regulatory lawyers and advisers to provide ongoing compliance support for fintech firms.
• Offer coordinated packages that combine regulatory asset reviews with annual statutory financial audits.
• Focus on identifying control gaps and recommending practical system improvements based on the firm’s business model.

Services

• CASS 5 audits for insurance separation compliance.
• CASS 6 audits for safe custody asset frameworks.
• CASS 7 audits for client money accounts.
• CASS 8 audits regarding corporate mandates.
• Preparation of Limited Assurance Reports (LARs) and Reasonable Assurance Reports (RARs).
• Safeguarding audit preparation for e-money institutions.

Contact Information

• Website: bkl.co.uk
• Address: 35 Ballards Lane, London, N3 1XW
• Phone: +44 (0)20 7832 0444
• Twitter: x.com/BKLtweets
• LinkedIn: www.linkedin.com/company/berg-kaprow-lewis-llp

Price Bailey

Price Bailey offers dedicated compliance reviews for businesses that hold, manage, or control client funds and custody assets. Their methodology centers on an initial evaluation of an organization’s internal control environment and checking operational processes against specific regulatory requirements. They encourage businesses to utilize structured tracking methods, like compliance mapping, to find potential failure points before formal testing begins.

The firm regularizes communication during the testing cycle by utilizing a dedicated team overseen by senior stakeholders. A major portion of their field procedures involves random sampling of transaction records, checking depository documentation, and verifying that external bank notices match standard regulatory formats. If administrative errors or system failures are uncovered, they compile structured schedules to help firms formulate corrective steps for oversight bodies.

Key Highlights

• Audit teams participate in regular FCA regulatory updates and specialized training webinars.
• Provide comprehensive breach reporting schedules that break down administrative errors and document client corrective actions.
• Review internal and external reconciliation records on a random sample basis to check system consistency.

Services

• CASS 6 safe custody asset compliance testing.
• CASS 7 client money assurance reviews.
• CASS 5 insurance product distribution testing.
• Limited assurance, reasonable assurance, and hybrid assurance reporting options.
• Reviewing and validating bank acknowledgement letters against regulatory templates.
• Transaction testing on sample deposit and withdrawal records.

Contact Information

• Website: www.pricebailey.co.uk
• Phone: 01223 565035
• E-mail: cambridge@pricebailey.co.uk
• Address: Tennyson House, Cambridge Business Park, Cambridge Cambridgeshire, CB4 0WZ
• Facebook: www.facebook.com/PriceBaileyLLP
• Twitter: x.com/price_bailey
• LinkedIn: www.linkedin.com/company/price-bailey
• Instagram: www.instagram.com/pbpeople

Prydis

Prydis delivers independent regulatory compliance reviews designed to verify the security of client assets and money held by authorized firms. Operating across regional offices and on a national scale, they structure their reviews around a commercial framework intended to preserve operational momentum while meeting oversight demands. Their process focuses on verifying that internal controls are strong enough to secure assets in the event of corporate insolvency.

The team utilizes both remote and on-site testing methods to accommodate different business structures, starting with early assessments to find control gaps before formal reporting begins. They focus heavily on sector-specific operations, working regularly with wealth management firms, investment platforms, and financial technology companies to align internal accounting records with regulatory expectations.

Key Highlights

• Offer a mix of remote and on-site audit delivery based on the client’s operational preferences.
• Include pre-audit gap assessments to catch system vulnerabilities before formal submissions.
• Focus on practical feedback aimed at improving governance frameworks and internal risk management.

Services

• CASS 5 compliance testing for insurance intermediaries.
• CASS 6 custody asset audits for platforms and wealth managers.
• CASS 7 client money reviews for investment businesses.
• Limited and reasonable assurance independent reporting.
• Control environment testing and walkthroughs for fintech platforms.
• Support with regulatory reporting submissions to the FCA.

Contact Information

• Website: prydis.com
• Phone: 01579 343215
• E-mail: mail@prydis.com
• Address: The Parade, Liskeard, Cornwall, UK, PL14 6AF
• LinkedIn: www.linkedin.com/company/prydis

Parker Russell UK

Parker Russell UK provides independent regulatory compliance and assurance services to financial businesses obligated to follow the Financial Conduct Authority (FCA) Client Assets Sourcebook (CASS) rules. Their workflow centers on analyzing structural risks, checking administrative workflows, and helping firms build defenses to protect client property during sudden insolvency scenarios. They coordinate their field procedures to establish an audit-ready state for firms facing annual examinations.

The team assists with the setup of oversight frameworks, reporting routines, and internal policy designs to match regulatory expectations. They focus on evaluating fund flows and checking how businesses manage and resolve reconciliation discrepancies. They also simulate external audit environments by conducting mock reviews to identify underlying control weaknesses before formal submissions occur.

Key Highlights

• Conduct simulated external audits to help firms discover and fix control issues early.
• Design tailored internal policies and governance structures for tracking client funds and custody assets.
• Support firms with the development and review of CASS Resolution Packs to address insolvency requirements.

Services

• CASS compliance assessments and operational gap analyses.
• Evaluation of internal calculations and external reconciliation systems.
• Governance framework design and breach management reporting support.
• Specialized track record assisting with skilled person reviews (s166).
• Advisory support for building regulatory asset and money frameworks.

Contact Information

• Website: parkerrussell.co.uk
• Facebook: www.facebook.com/parkerrusselluk
• Twitter: x.com/ParkerRussellUK
• Address: Level 30, The Leadenhall Building, 122 Leadenhall St, London EC3V 4AB, United Kingdom
• Phone: +44 (0)20 7378 7500
• Email: info@parkerrussell.co.uk

Hillier Hopkins

Hillier Hopkins handles specialized compliance reporting for investment firms, payment service providers, and insurance intermediaries managing client assets. Their procedures focus on identifying an organization’s specific regulatory classification to determine the precise type of independent assurance report needed for the FCA. They maintain a strict schedule to ensure all reports meet the four-month submission deadline following the close of a firm’s reporting period.

The firm addresses newer regulatory transitions, such as the implementation of independent qualified external audits for electronic money and payment institutions under updated safeguarding rules. Their teams verify compliance by assessing various client trust accounts, accounting records, and total transaction volumes to determine whether a firm requires specific formal reporting or falls within regulatory exemption brackets.

Key Highlights

• Handle the direct submission of required assurance reports to the FCA for designated investment firms.
• Provide compliance validation for electronic money institutions dealing with updated safeguarding standards.
• Adjust evaluation methods based on specific financial thresholds, such as the 100,000 GBP relevant funds limit for payment firms.

Services

• Reasonable assurance reporting for firms holding client money and safe custody assets.
• Limited assurance reporting for businesses permitted to hold assets but claiming not to do so.
• Hybrid assurance reporting combining different asset protection elements.
• CASS 5 compliance evaluations for mortgage and general insurance companies.
• CASS 6 and CASS 7 assurance reviews for designated investment firms.

Contact Information

• Website: hillierhopkins.co.uk
• Address: 45 Pall Mall, London, SW1Y 5JG
• Phone: +44 (0)330 024 3200
• Email: hi@hhllp.co.uk

Johnston Carmichael

Johnston Carmichael delivers dedicated regulatory reviews for financial businesses that must demonstrate robust governance over client assets. Their methodology accounts for how individual business models, operational setups, and digital tools affect the way a firm applies client asset rules. The team incorporates direct input from senior stakeholders throughout the testing cycle to maintain uniform evaluation quality.

The firm integrates software assessments into its compliance reviews, using a specialized information technology audit team to check application safety alongside standard asset tracking procedures. After completing field testing, they issue detailed management letters containing observations and practical feedback to help firms align their accounting systems with evolving regulatory expectations.

Key Highlights

• Combine specialized financial auditors with an IT audit team to review application controls and systems together.
• Supply detailed management letters containing system observations and practical structural feedback after audits.
• Provide guidance on new regulatory adjustments, including upcoming safeguarding modifications for payment providers.

Services

• Reasonable and limited assurance CASS audit engagements.
• Specialized compliance testing for investment management and wealth firms.
• Safe custody (CASS 6) and client money (CASS 7) governance reviews.
• IT control assessments across core financial systems and applications.
• Regulatory support and educational workshops regarding new safeguarding rules.

Contact Information

• Website: johnstoncarmichael.com
• Facebook: www.facebook.com/JohnstonCarmichael
• Twitter: x.com/JC_Accountants
• LinkedIn: www.linkedin.com/company/johnston-carmichael-chartered-accountants-and-business-advisers
• Instagram: www.instagram.com/johnston_carmichael
• Address: Si Mathavan, Internal Audit Partner, Birchin Court, 20 Birchin Lane, London EC3V 9DU
• Phone: 0203 7144 350

Saffery

Saffery provides statutory accounting and specialized client asset review services to firms navigating the supervisory demands of the Financial Conduct Authority (FCA). Their methodology concentrates on checking how well an organization’s systems protect client funds and safe custody assets from operational degradation or sudden business collapse. They structure their review protocols to directly check internal controls against the strict rules detailed across the FCA CASS and Supervision sourcebooks.

The team handles multi-stage assurance procedures that frequently incorporate continuous check-ins during the financial year alongside post-period validation tests. They help various businesses-including wealth managers, retail banks, and insurance brokerages-prepare for upcoming regulatory changes, such as proposed compliance transformations affecting payment institutions and electronic money networks. They prioritize early alignment meetings to manage workload volumes, as all finalized asset reports require submission within a strict four-month post-period deadline.

Key Highlights

• Coordinate both interim visits and year-end procedures to manage reporting volumes for fast-turnaround deadlines.
• Map internal management processes directly to the specialized Business Standards and Regulatory Processes blocks of the FCA handbook.
• Detail and catalog all detected administrative variances directly onto the final regulatory assurance record for submittal.

Services

• Reasonable assurance reporting for entities actively holding client funds or custody property.
• Limited assurance reporting for designated investment operations with restricted asset permissions.
• Hybrid compliance reporting covering alternating transactional permission windows.
• Specialized regulatory preparation for e-money institutions anticipating safeguarding rule updates.
• Technical planning workshops combining routine statutory audits with specialized client asset reviews.

Contact Information

• Website: www.saffery.com
• Phone: +44 (0)117 915 1617                                                                  
• E-mail: info@saffery.com
• Address: St Catherine’s Court, Berkeley Place, Clifton, Bristol BS8 1BQ, UK
• LinkedIn: www.linkedin.com/company/saffery
• Instagram: www.instagram.com/saffery_uk

PKF Littlejohn

PKF Littlejohn delivers technical audit and compliance framework reviews tailored for investment managers, brokers, and private equity portfolio operations handling safe custody assets. Their audit workflow targets an early assessment of the firm’s central control matrices to verify that regulatory policies match day-to-day handling operations. They focus on evaluating structural documentation, advising businesses to maintain precise internal matrices to avoid recordable compliance deficiencies.

The firm regularizes field operations by evaluating operational readiness across critical support sectors, checking variables like corporate resolution packs and annual vendor due diligence records. Their testing methodology reviews internal breach registers to ensure both the technical details and resolution timelines are clearly stated. They also incorporate evaluations of continuous employee training programs to verify that staff members stay informed about regulatory changes.

Key Highlights

• Request and evaluate up-to-date risk and controls matrices during the initial planning phase to guide field sampling.
• Audit ongoing corporate training records to confirm staff competencies match regulatory safety requirements.
• Review and verify rolling CASS Resolution Packs to ensure asset tracking documentation supports emergency insolvency scenarios.

Services

• CASS 6 safe custody asset structure testing.
• CASS 7 client money account tracking and assurance reviews.
• Compliance health checks and limited assurance portfolio reviews.
• Validation of banking institution due diligence and bank acknowledgement letters.
• Analysis and structural formatting of corporate breach registers.
• Collaborative systems review combining core financial testing with specialized IT assurance teams.

Contact Information

• Website: www.pkf-l.com
• Phone: 0161 552 4220
• Address: 11 York Street, Manchester, M2 2AW
• Instagram: www.instagram.com/pkf.littlejohn
• Twitter: x.com/PKF_Littlejohn
• Linkedin: www.linkedin.com/company/littlejohn

Thistle Initiatives

Thistle Initiatives specializes in regulatory consulting and compliance monitoring support for businesses required to manage client assets under the FCA framework. They operate across multiple financial sectors-including digital assets, credit markets, and platform services-to evaluate control networks and locate potential gaps in asset segregation processes. Their services emphasize procedural preparation, helping firms adjust internal controls before external audit teams begin their seasonal fieldwork.

The team utilizes diagnostics like high-level health checks and detailed procedural breakdowns to help firms update their operational workflows. They focus on improving internal oversight tools, reviewing monthly regulatory returns, and tracking data validation routines. They also provide targeted compliance workshops to help individual managers and functional teams align daily operations with current regulatory manuals.

Key Highlights

• Deliver periodic or one-off compliance health checks to evaluate corporate control standards.
• Pre-screen audit documentation and detected breach logs before external reporting teams finalize their reviews.
• Provide tailored face-to-face and online training modules covering specific investment and insurance compliance rules.

Services

• CASS health check audits and structural gap analyses.
• Assessment and design of functional CASS risk matrices.
• Operational reviews of written corporate procedures and compliance monitoring tools.
• Independent validation and updates for CASS Resolution Packs.
• Assessment of client money asset returns (CMAR) reporting workflows.
• Remedial support and advisory services for resolving noted compliance failures.

Contact Information

• Website: www.thistleinitiatives.co.uk
• Address: 2nd Floor, 4 St. Paul’s Churchyard, London, EC4M 8AY
• Phone: 020 7436 0630
• Linkedin: www.linkedin.com/company/thistle-initiatives

Conclusion

At the end of the day, picking a CASS 6 audit firm isn’t something you want to rush through just to cross it off your annual compliance list. Because the FCA views asset safeguarding failures in such rigid, black-and-white terms, the relationship you have with your auditor matters just as much as their technical credentials. When firms outgrow their current setups or face shifting rules-like the incoming safeguarding updates we are seeing roll out this year-they look for providers who can challenge their processes without completely throwing off daily operations. You need a team that knows how to look at an IT system or a reconciliation sheet and spot the weak points before they turn into recordable breaches.

That is exactly why we put this guide together. Instead of just listing names, we wanted to show you how different providers handle everything from early gap analysis to complex tech reviews. Some of these firms bring massive international networks to the table, while others offer specialized, hands-on support that fits neatly alongside your existing internal compliance teams. Hopefully, seeing these approaches broken down side by side gives you a clearer idea of what to look for-and helps you find a partner who actually understands the operational realities of your business.