CASS 6 Audit Firms in London: Companies and Services Guide

Choosing a CASS 6 audit provider in London is not just a formal reporting step for FCA-regulated firms. It can affect how clearly a business understands its custody arrangements, how well it protects client assets, and how prepared it feels when regulatory scrutiny increases.

London has a broad mix of audit and assurance providers, from large professional services firms with financial services teams to specialist practices that work closely with investment firms, brokers, asset managers, and other regulated businesses. Each firm may bring a different level of CASS experience, sector knowledge, reporting style, and practical support.

This guide highlights a selection of CASS 6 audit companies serving firms in and around London. It is not intended as a strict ranking. The aim is to give useful context – who these providers are, the types of organisations they may support, and the areas of CASS 6 work where they are most relevant.

Acumon

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

The firm supports organisations of different sizes and structures, from growing owner-managed businesses and charities to larger corporate groups and entities operating in regulated sectors. Audit work is carried out in line with International Standards on Auditing (UK), using a structured, risk-focused approach that considers the organisation, its controls, and the reporting environment in which it operates.

For firms in the financial services sector, CASS 6 audit work is linked to the FCA Client Assets Sourcebook rules on custody assets. These rules apply where a firm holds or controls safe custody assets for clients, and the audit process helps assess whether arrangements for recording, safeguarding, reconciling, and reporting client assets are operating as required.

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

Alongside its UK audit registration, Acumon also 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 work with international corporate groups where the structure includes entities across more than one jurisdiction.

International groups often include a mix of UK operating companies, offshore holding entities, investment vehicles, and regulated businesses. In sectors such as investment management, technology, energy, and international trade, audit work may need to take account of cross-border reporting, consolidation, governance, and regulatory requirements.

Acumon works with finance teams, boards, and senior management to support statutory audit obligations while also helping organisations review financial reporting processes, governance arrangements, internal controls, and regulatory compliance as they develop.

Audit Capabilities

Acumon provides external audit, assurance, and due diligence services across a broad range of sectors, entity types, and ownership structures. For CASS 6 audit engagements, this may include reviewing how a firm records and reconciles custody assets, how responsibilities are allocated internally, and how client asset controls are documented and monitored. 

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 engagements are usually overseen by senior audit professionals who remain closely involved throughout the work, from planning and risk assessment through to reporting and final review.

Regulatory Licences and Registrations

Acumon holds a number of audit registrations that allow it to support organisations with UK and international audit requirements. These registrations are especially relevant for groups with regulated entities, offshore structures, investment vehicles, or operations in more than one jurisdiction.

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

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

Core Services

In addition to statutory external audit, Acumon provides services that support financial reporting, governance, regulatory assurance, and control review.

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 carried out alongside practical discussions with management and boards about reporting processes, governance frameworks, and the strength of internal controls.

Many organisations first engage with statutory audit requirements as they grow and move beyond the audit exemption thresholds under the Companies Act. Regulated financial services firms may also need specialist audit or assurance input where client money, custody assets, or wider regulatory obligations form part of their operating model.

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 organisations prepare their records, reporting systems, governance documentation, and control processes before the audit process begins.

Contact Information

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

Gravita

Gravita provides a comprehensive suite of audit and advisory services tailored for regulated entities operating within the financial services sector. Their approach relies on risk-based methodologies designed to address specific operational vulnerabilities, manage complex compliance demands, and fulfill regulatory reporting deadlines ahead of schedule. By combining robust tools with proactive communication, they aim to bring transparency and efficiency to firms navigating oversight from the Financial Conduct Authority (FCA) and the Prudential Regulation Authority (PRA).

Gravita maintains a strong focus on specialist frameworks beyond standard statutory requirements, notably conducting audits for businesses with Client Asset Sourcebook (CASS) permissions, including safe custody and client money rules. They also handle specialized safeguarding audits for electronic money institutions and digital payment providers. Through their global network, DFK International, they support organizations with multi-jurisdictional operations, combining localized regulatory knowledge with international reach while offering practical insights for business improvement.

Key Highlights

• Risk-based audit methodology focusing on core operational and regulatory risks
• Global reach and support through membership in the DFK International network
• Comprehensive support across multiple CASS frameworks, including rules for insurance distribution and client assets
• Seamless client onboarding processes with an emphasis on timely regulatory submissions
• Inclusions of pragmatic operational improvements and risk identification within audit reporting

Services

• Financial services audits and statutory accounting
• CASS 5, CASS 6, CASS 7, and CASS 15 compliance audits
• Safeguarding audits for e-money and digital payment businesses
• Bookkeeping and regulatory return assistance
• Corporate tax advice and business consultancy
• Succession planning for regulated financial entities

Contact Information

• Website: www.gravita.com
• Email: hello@gravita.com
• LinkedIn: www.linkedin.com/company/gravita-uk
• Twitter: x.com/TeamGravita
• Instagram: www.instagram.com/gravita_uk
• Phone: 020 7330 0000
• Address: Aldgate Tower, 2 Leman Street, London, E1 8FA

Price Bailey

Price Bailey delivers specialized assurance and audit services designed to help financial firms satisfy their obligations under the FCA Client Assets Sourcebook rules. Their operational structure relies on dedicated teams guided by senior practitioners who understand the distinct technical infrastructure and systems used by regulated businesses. They place a strong emphasis on early risk and breach identification, providing organizations with the necessary timeline to address compliance gaps before submitting final documentation to regulatory bodies.

Price Bailey centers its methodology on a comprehensive evaluation of a firm’s internal control environment, which includes reviewing systems, evaluating CASS mapping exercises, and conducting detailed walkthroughs of asset handling procedures. A significant portion of their fieldwork involves reviewing internal and external reconciliations on a random basis, confirming account segregation, and verifying bank acknowledgment letters against official regulatory templates. They work across a variety of business structures, adjusting their procedures to meet the specific limited, reasonable, or hybrid assurance standards required by a company’s specific permissions.

Key Highlights

• Experienced CASS audit teams with targeted training in FCA regulatory updates
• Explicit focus on early breach detection and detailed breaches schedule reporting
• Practical control testing, including random internal and external reconciliation reviews
• Verification of client bank account acknowledgment letters against CASS templates
• Structured approach covering investment businesses, FX trading, crowdfunding platforms, and insurance distributors

Services

• CASS 6 (safe custody assets) and CASS 7 (client money) assurance reviews
• CASS 5 insurance product distribution audits
• Limited, reasonable, and hybrid assurance reporting for the FCA
• Safeguarding audits for payment service providers and e-money institutions
• Statutory financial audits for single entities and corporate groups
• Control environment assessment and CASS risk mapping support

Contact Information

• Website: www.pricebailey.co.uk
• Phone: 020 7065 2660
• E-mail: city@pricebailey.co.uk
• Address: 8th Floor, Dashwood House, 69 Old Broad Street, London EC2M 1QS
• Facebook: www.facebook.com/PriceBaileyLLP
• Twitter: x.com/price_bailey
• LinkedIn: www.linkedin.com/company/price-bailey
• Instagram: www.instagram.com/pbpeople

Hillier Hopkins

Hillier Hopkins provides specialized regulatory assurance reports for firms bound by the FCA Client Assets Sourcebook regulations, regardless of whether those organizations require a standard statutory financial audit. Their work provides an independent assessment of compliance, which is submitted directly to the regulator or delivered to the firm depending on the specific category of authorization held. They assist businesses in determining their exact reporting obligations under tight four-month deadlines from the end of the financial reporting period.

Hillier Hopkins spans its expertise across multiple sectors within the financial services industry, including designated investment firms, mortgage brokers, general insurance businesses, and payment institutions. They actively assist companies in adapting to updated regulatory environments, such as the shifting safeguarding rules that bring electronic money institutions and firms under the Payment Services Directive into a structured external audit framework. By focusing on asset levels and trust structures, they align their testing with the specific limited, reasonable, or hybrid assurance reporting requirements dictated by the firm’s operations.

Key Highlights

• Specialized reporting for designated investment firms handling client money and custody assets
• Direct submission of completed assurance documentation to the FCA for investment practices
• Guidance on threshold limits and reporting exemptions for financial and personal investment firms
• Dedicated support for payment and e-money firms adapting to new external safeguarding audit regimes
• Independent membership in TGS, an international network of professional business advisors

Services

• CASS 6 safe custody asset and CASS 7 client money assurance audits
• CASS 15 safeguarding assurance reports for EMI and PSD entities
• CASS 5 compliance reporting for mortgage and general insurance firms
• Reasonable, limited, and hybrid assurance reviews
• FCA regulated business advisory and statutory audit services
• Control assessment for non-statutory and statutory trust client accounts

Contact Information

• Website: hillierhopkins.co.uk
• Address: 45 Pall Mall, London SW1Y 5JG
• Phone: +44 (0)20 7930 7797
• Email: hi@hhllp.co.uk

PKF Littlejohn

PKF Littlejohn provides specialized CASS audit and advisory services tailored for wealth and asset managers, private equity firms, and broker-dealers. Their approach emphasizes structured preparation to assist firms in meeting the strict four-month submission deadline required by the Financial Conduct Authority (FCA). They focus on facilitating early collaboration between compliance and IT departments, allowing for interim reviews that identify potential process gaps and system changes well in advance of the financial year-end.

PKF Littlejohn prioritizes a controls-based methodology that relies heavily on a firm’s internal risk and controls matrix to assess overall asset protection frameworks. Their fieldwork includes evaluation of client asset resolution packs required under CASS 10, alongside annual reviews of bank acknowledgment letters and third-party due diligence. They also evaluate internal training protocols and breach registers to confirm that companies maintain qualitative and quantitative records capable of satisfying regulatory scrutiny.

Key Highlights

• Focus on early audit timetabling and interim reviews to capture system updates ahead of year-end
• Thorough evaluation of internal risk and control matrices to guide the audit risk assessment
• Systematic review of CASS 10 resolution packs to verify insolvency preparedness
• Validation of internal CASS training data and employee attendance records for control assessments
• Guidance on constructing detailed breach registers to simplify reporting workflows

Services

• CASS 6 and CASS 7 compliance audits and health checks
• Statutory financial audits for asset managers and funds
• Limited assurance reviews and internal controls testing
• IT assurance and specialized systems reviews
• Structured tax advice and corporate planning for financial firms
• Due diligence support for banking and custodian arrangements

Contact Information

• Website: www.pkf-l.com
• Phone: 020 7516 2200
• Address: 30 Churchill Place, London E14 5RE
• Instagram: www.instagram.com/pkf.littlejohn
• Twitter: x.com/PKF_Littlejohn
• Linkedin: www.linkedin.com/company/littlejohn

Johnston Carmichael

Johnston Carmichael delivers dedicated CASS and safeguarding audit services designed to handle the operational complexities of growing and established investment firms. They approach compliance from a business-model perspective, recognizing that a firm’s application of safeguarding rules depends on its distinct technology setup, corporate governance, and day-to-day transaction flows. They prioritize continuous staff development and long-term client relationships to maintain stable technical insight across successive compliance cycles.

Johnston Carmichael integrates specialized IT audit specialists directly into their CASS engagements to review controls across critical payment systems and business software. This combined review model allows them to trace risks across technical architectures and highlight processing anomalies early in the lifecycle. At the conclusion of their fieldwork, they issue detailed management letters containing operational recommendations intended to strengthen internal procedures and align corporate practices with current industry standards.

Key Highlights

• Integrated team structure combining general CASS auditors with specialized IT control reviewers
• Active integration of senior team members to guide decision-making at every audit phase
• Focus on long-term client relationships to provide stability in technical compliance reviews
• Experience across diverse models including e-money providers, investment managers, and insurance intermediaries
• Provision of comprehensive management letters detailing practical operational changes

Services

• CASS 6 safe custody asset and CASS 7 client money audits
• CASS 15 safeguarding assurance for payment and e-money institutions
• Reasonable and limited assurance regulatory reporting for the FCA
• Technical control environment assessments and IT workflow tracking
• Regulatory advisory services for market entry and product diversification
• Asset management and investment trust statutory auditing

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

Parker Russell

Parker Russell provides comprehensive CASS audit and advisory services to financial firms that hold client money or custody assets. Their focus centers on helping companies achieve regulatory compliance, strengthen internal control frameworks, and establish a consistent, audit-ready position. They work with businesses to integrate safeguarding processes, corporate governance, and reporting frameworks, which helps reduce regulatory exposure and clarify fund flows in line with Financial Conduct Authority (FCA) expectations.

Parker Russell relies on a structured approach that prepares firms for formal external reviews through gap analysis, compliance assessments, and mock audits. They actively support the creation and optimization of client money and custody structures, including written policies and governance models. Additionally, their work extends to evaluating internal calculations, checking external reconciliations, and designing CASS resolution packs alongside wind-down plans to assist with asset tracking in insolvency scenarios.

Key Highlights

• Focus on regular mock audits aligned with external review methods to catch process issues early
• Assessment and remediation support to help firms prepare for formal annual CASS audits
• Structuring and verification of CASS resolution packs for rapid asset tracking during insolvency
• Strengthening of internal calculations, break resolutions, and external transaction reconciliations
• Framework adjustments designed to improve management oversight and regulatory breach handling

Services

• CASS audit readiness assessments and gap analysis
• Independent CASS reviews and mock audit testing
• Client money and custody framework design
• Internal calculations and external reconciliation reviews
• CASS resolution pack development and wind-down planning
• Governance, reporting, and breach management oversight

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

Saffery

Saffery delivers specialist CASS audit and assurance services aimed at helping regulated firms protect client assets from loss, theft, or diminution. They position their work around the core statutory objectives of the FCA, assisting investment businesses, insurance intermediaries, and banks in verifying that their operational systems remain compliant. They help management teams navigate the complexities of the FCA Handbook, focus on strict reporting deadlines, and plan their compliance procedures well ahead of the financial year-end.

Saffery structures its procedures around reasonable assurance engagements, limited assurance reviews, or hybrid reporting paths depending on the exact permissions a firm holds. Their teams conduct extensive transaction reviews, checking systems for rule compliance and verifying that client money is held correctly in segregated accounts. They also look at emerging regulatory movements, helping electronic money and payment institutions prepare for evolving external safeguarding frameworks that require independent qualified audits.

Key Highlights

• Delivery of reasonable assurance audits involving extensive procedures and regular interim visits
• Analytical and inquiry-based limited assurance reviews for firms with non-holding permissions
• Testing across multiple regulated areas including investment management, banking, and insurance
• Experience with multi-market structures through international network membership with Nexia
• Focus on early planning to manage tight four-month regulatory submission deadlines

Services

• Reasonable, limited, and hybrid CASS assurance reporting
• Review of client funds segregation and bank account structures
• Assistance with emerging safeguarding audit regimes for electronic money institutions
• Statutory financial auditing for commercial, owner-managed, and international businesses
• Identification and tracking of regulatory rule breaches for management reporting
• Systems and controls evaluation for FCA-regulated entities

Contact Information

• Website: www.saffery.com
• Phone: +44 (0)20 7841 4000                                                                                                   
• E-mail: info@saffery.com
• Address: 71 Queen Victoria Street, London EC4V 4BE, UK
• LinkedIn: www.linkedin.com/company/saffery
• Instagram: www.instagram.com/saffery_uk

Thistle Initiatives

Thistle Initiatives provides specialized compliance audit support and advisory services focused on the FCA client money and custody assets rules. They work across multiple financial domains, including investments, credit, digital assets, and general insurance, to help businesses keep their operations aligned with the CASS sourcebook rules. Their work is designed to help firms maintain high compliance standards at all times, preventing regulatory failures through proactive control tracking and proportionate recommendations.

Thistle Initiatives conducts targeted CASS health check audits that can range from high-level operational overviews to complete process evaluations. They assist firms by reviewing written procedures, building risk matrices, and evaluating compliance monitoring systems. For businesses anticipating an external audit, they offer hands-on preparation support, help evaluate identified breaches before reports are finalized, and provide tailored face-to-face or online training for relevant compliance staff and senior management.

Key Highlights

• Provision of targeted CASS health check audits available on a periodic or one-off basis
• Pre-audit preparation support to organize documentation before external reviewers arrive
• Development and independent review of corporate CASS risk matrices and written compliance manuals
• Advisory services on external auditor selection and analysis of preliminary audit findings
• Face-to-face and online training programs tailored for team members and senior management

Services

• CASS health checks and process evaluations
• CASS risk matrix development and procedures review
• CASS resolution pack creation and assessment support
• External audit preparation and findings remediation
• CMAR reporting and compliance monitoring reviews
• Face-to-face and digital CASS training courses

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

Selecting the right CASS compliance partner in London is never a decision to rush through on a Friday afternoon. When you are looking at safe custody assets under CASS 6, the Financial Conduct Authority (FCA) expects absolute precision in your internal controls, daily reconciliations, and the maintenance of your resolution pack. The reality is that different firms need entirely different things from their auditors. An investment boutique might only require a limited assurance review to confirm they do not actively hold client funds, whereas a larger trading platform or a newly regulated payment institution facing the latest safeguarding updates will need a highly intensive, reasonable assurance process with regular interim field visits.

This guide serves as a practical blueprint because it cuts through standard marketing boilerplate to show you exactly how these specialists handle real-world operational challenges. When assessing your options, the key is matching the complexity of your financial structures with an advisory firm’s specific tactical strengths – whether that is Parker Russell’s hands-on framework design, Saffery’s deep institutional audit history, or Thistle Initiatives’ proactive compliance health checks. With the FCA ramping up enforcement and strict four-month post-year-end deadlines looming, picking a partner who genuinely understands your sector is what keeps your operational integrity intact and ensures you stay firmly on the right side of the regulatory line.