Tax Dispute Resolution Companies in London: Firms and Services Guide (2026)
AC
Acumon Chartered Accountants·13 min read
This practical guide reviews companies providing tax dispute resolution services in London for businesses and individuals facing HMRC enquiries, investigations, appeals and other contested tax matters. It is an overview rather than a strict ranking, with the focus on giving useful context rather than ranking companies by a single measure. The selection ranges from large companies with broad tax, legal and advisory capabilities to narrower specialists concentrating on HMRC investigations, ADR, appeals and tax litigation. Each section looks at the company, the clients it serves, its relevant strengths and the scope of its tax dispute work. The aim is to make the differences easier to compare and help readers identify an option that matches the nature and complexity of their dispute.
Acumon
Acumon is a UK company of chartered accountants and registered auditors providing tax dispute resolution services from its London practice. The company supports businesses and individuals where a disagreement with HMRC has developed around an assessment, enquiry conclusion, penalty, ruling, VAT position, employment status or another tax matter.
The tax dispute service covers the stages between an initial disagreement and formal appeal. Acumon can review the technical position, organise supporting evidence, manage correspondence with HMRC and determine whether the matter is better addressed through negotiation, Alternative Dispute Resolution (ADR), statutory review or tribunal proceedings. Several of its tax advisers previously worked for HMRC, giving the team experience of disputes from both sides of the process.
Acumon also accepts disputes that have already progressed under another adviser. In these situations, the company can review previous correspondence, establish what has already been conceded, identify outstanding deadlines and reassess the technical arguments before deciding the next procedural step.
The scope extends beyond the disputed tax itself. Acumon handles penalty classifications, interest, disclosure-related reductions and time-to-pay arrangements where these form part of the eventual settlement. It can also challenge information notices, VAT assessments and IR35 determinations where HMRC and the taxpayer have reached different positions.
Where negotiation does not resolve the matter, Acumon can prepare and manage First-tier Tribunal appeals, involving specialist counsel where required. Its wider tax and HMRC investigation services allow enquiry-stage work and formal dispute resolution to be handled within the same professional practice.
Tax Dispute Resolution Capabilities
Acumon provides support across a range of disputed HMRC decisions and formal resolution routes.
These include:
Disputed enquiry conclusions and assessments
Discovery assessment challenges
Penalty disputes and behaviour classifications
Alternative Dispute Resolution applications and representation
Statutory reviews and formal appeals
First-tier Tribunal case preparation and management
VAT assessment and security demand disputes
IR35 and employment status determinations
Information notice challenges
Time-to-pay negotiations linked to settlement
Acumon can manage the procedural and technical sides of a dispute while maintaining the required appeal and review deadlines.
Regulatory Licences and Registrations
Acumon provides tax dispute services within a UK chartered accountancy and registered audit practice. Its professional and regulatory position includes:
ICAEW Registered Audit status
Chartered Accountancy services
Chartered Tax Adviser expertise within the tax team
UK Tax advisory and compliance services
HMRC Investigation and dispute representation
Acumon UK Limited is registered to carry out audit work by the ICAEW and operates its London office from Ealing.
Core Services
Alongside tax dispute resolution, Acumon provides tax, accounting, audit and advisory services that can support the wider financial and compliance issues surrounding an HMRC dispute.
These include:
Corporate and personal tax
Tax compliance
HMRC tax investigations
VAT services
Payroll and employment taxes
Accounting and bookkeeping
Audit and assurance
Risk and technology assurance
Specialist advisory services
Acumon can combine dispute work with investigation and tax compliance support where the underlying issue extends beyond a single HMRC decision.
Acumon works with clients that are:
Challenging an HMRC assessment or enquiry conclusion
Responding to disputed penalties
Considering Alternative Dispute Resolution
Requesting a statutory review of an HMRC decision
Preparing an appeal to the First-tier Tribunal
Contesting VAT, IR35 or information notice decisions
Transferring an existing dispute from another adviser
Negotiating settlement and payment arrangements with HMRC
Reviewing the technical position and procedural deadlines early can help Acumon preserve available appeal routes and establish the evidence needed for negotiation, review or tribunal proceedings.
Address: 1-2 Craven Road, Ealing, London, W5 2UA, UK
PwC UK
PwC provides tax dispute resolution services covering the prevention, management and resolution of disputes with HMRC and other tax authorities. Its multidisciplinary approach brings together tax advisers, accountants, solicitors, economists, former HMRC inspectors and other specialists.
The work extends from enquiry management and voluntary disclosures to negotiations, ADR and litigation. PwC also handles cross-border disputes and matters involving competent authority procedures and Mutual Agreement Procedure, making its offering relevant to larger companies dealing with disputes that extend beyond one UK tax issue.
Specialization: Corporate and cross-border tax disputes
Client types: Businesses and taxpayers with complex contentious tax matters
Location: London and wider UK
Notable focus: Combined tax, legal and dispute management support
Contact Information
Website: www.pwc.co.uk
Phone: +44 (0)20 7583 5000
Address: 1 Embankment Place, London, WC2N 6RH, United Kingdom
LinkedIn: www.linkedin.com/company/pwc-uk
Facebook: www.facebook.com/PwCUK
Instagram: www.instagram.com/pwc_uk
Moore Kingston Smith
Moore Kingston Smith has a dedicated tax dispute resolution practice supporting businesses and individuals through HMRC enquiries and investigations. Its services include ordinary tax enquiries as well as COP8 and COP9 investigations, voluntary disclosures and Alternative Dispute Resolution.
The team can manage correspondence with HMRC, review information requests, prepare evidence and support clients through mediation. Where a dispute becomes more serious, its work can extend to formal review and tribunal-related matters. The firm’s tax dispute lead and general contact details are based in London.
RSM UK provides tax risk and investigation support for taxpayers dealing with HMRC enquiries and contentious matters. Its dispute specialists work on compliance investigations, HMRC information requests, significant penalty issues and serious investigations conducted under Codes of Practice 8 and 9.
Its advisers can also assist with ADR and tax tribunal procedures where an enquiry cannot be resolved through ordinary correspondence or negotiation. This makes RSM relevant to both investigation work and disputes that have progressed into formal challenge procedures.
Key Facts
Core services: Tax investigations, HMRC enquiries, ADR, tribunal support
Specialization: HMRC disputes and investigations
Issues covered: COP8, COP9, penalties, information requests
Location: London and wider UK
Notable focus: Managing contentious HMRC enquiries through settlement or appeal
Contact Information
Website: www.rsmuk.com
Phone: +44 (0)20 3201 8000
Address: 25 Farringdon Street, London, EC4A 4AB
LinkedIn: www.linkedin.com/company/rsm-uk
Instagram: www.instagram.com/rsm.uk
BDO
BDO has a dedicated Tax Dispute Resolution team advising on HMRC compliance checks, nudge letters, technical disputes, historical tax problems and allegations of tax fraud. Its London specialists include tax professionals with previous senior HMRC investigation experience.
The firm’s approach covers investigation of the underlying facts, technical analysis, negotiation and use of HMRC’s ADR process where suitable. If agreement cannot be reached, BDO can support appeals through the Tax Tribunals and courts while working with the client’s legal advisers.
Client types: Private clients, businesses and multinational companies
Location: London and nationwide
Notable focus: Dedicated dispute specialists and former HMRC personnel
Contact Information
Website: www.bdo.co.uk
Phone: 020 7486 5888
Address: 55 Baker Street London, W1U 7EU, United Kingdom
LinkedIn: www.linkedin.com/company/bdo-llp
Instagram: www.instagram.com/bdo_uk
S&W
S&W provides tax dispute resolution support from its London practice for individuals and businesses facing investigations, enquiries or technical disagreements with HMRC. Its service distinguishes between serious investigations, routine tax enquiries, formal tax disputes and disclosures.
For contentious matters, the team advises on factual and technical disagreements and can support statutory reviews, appeals and litigation. It also handles investigations conducted by HMRC’s Fraud Investigation Service under Codes of Practice 8 and 9.
Specialization: Serious tax investigations and contentious tax matters
Issues covered: COP8, COP9, technical disputes
Location: London
Notable focus: Support from enquiry through reviews, appeals and litigation
Contact Information
Website: www.swgroup.com
Phone: +44 204 617 55 00
Address: 45 Gresham St, London EC2V 7BG
LinkedIn: www.linkedin.com/company/swgroupuk
Twitter: x.com/S_W_Group
HaysMac
HaysMac includes Tax Dispute & Resolution Services within its wider tax practice. The London company advises private clients, businesses and trusts that are subject to HMRC investigations or other tax disputes.
Its support covers the period from initial HMRC contact through to resolution, allowing the company to handle correspondence and investigation issues while drawing on specialists from its wider tax practice when disputes concern particular areas such as VAT or corporate taxation.
KPMG combines tax advisory and legal capabilities for disputes involving HMRC. Its tax disputes and litigation practice covers direct and indirect taxes, including corporate tax, VAT, capital gains tax, customs and other contentious matters.
The company can help organise evidence, respond to HMRC information requests, challenge assessments, develop dispute strategies and seek settlements. Its team also handles ADR and litigation before the Tax Tribunal and higher courts. KPMG has London-based lawyers and advisers focused specifically on tax dispute resolution, including accredited mediators and former HMRC professionals.
MHA offers a specific Tax Dispute Resolution service for individuals and businesses dealing with HMRC. The work includes early assessment of a dispute, tax reviews, direct liaison and negotiation with HMRC, statutory review representation and ADR support.
Where a case progresses further, the team can provide representation at the Tax Tribunal. MHA also offers tax investigation support and compliance reviews designed to establish an audit trail and identify potential weaknesses before or during an HMRC enquiry.
Crowe UK has a Tax Disputes and Investigations practice with London-based specialists advising individuals and businesses on HMRC enquiries, disclosures and contested tax matters. The team handles statutory enquiries, COP8 and COP9 investigations, voluntary disclosures, assessments and penalties.
For matters that cannot be resolved through routine enquiry correspondence, Crowe can support mediation, ADR and tribunal-related proceedings. Its London tax disputes team includes advisers with previous HMRC experience who work on both investigation management and formal challenges to HMRC decisions.
Forvis Mazars provides tax dispute resolution services for individuals, sole traders, partnerships, trusts and companies dealing with HMRC investigations and disputed decisions. Its work includes routine compliance checks as well as COP8 and COP9 investigations, discovery assessments and R&D-related enquiries.
The company also advises on appeals against HMRC decisions, penalties, Schedule 36 information requests and voluntary disclosures. More formal dispute work can involve ADR and litigation, while its international tax specialists can assist with procedures such as Mutual Agreement Procedure where double taxation is involved.
Price Bailey supports individuals and businesses during HMRC investigations through its Tax Investigation Service. The service covers professional representation during a range of HMRC interventions, including Self Assessment enquiries and investigations involving business records, PAYE and VAT.
The emphasis is primarily on investigation support and representation rather than a standalone litigation practice. This makes Price Bailey most relevant where the immediate requirement is managing an HMRC enquiry, preparing responses and defending the taxpayer’s position during the investigation process.
Key Facts
Core services: HMRC enquiry and investigation representation
Specialization: Tax investigation support
Client types: Individuals and businesses
Location: London and wider UK service coverage
Notable focus: Professional representation during HMRC interventions
Deloitte’s Tax Controversy practice advises businesses and individuals throughout the tax dispute lifecycle, from the opening of an HMRC audit through settlement and litigation. Its UK team combines tax specialists with former tax authority personnel, solicitors, ADR specialists and tax litigators.
Settlement work can involve financial analysis, engagement with HMRC, ADR, penalty issues and formal settlement documentation. Where litigation is required, Deloitte supports appeals, judicial reviews and other tax proceedings from the First-tier Tribunal through higher courts. The company can also coordinate tax controversies involving multiple jurisdictions.
Specialization: Complex and cross-border tax disputes
Client types: Businesses and individuals
Location: London and wider UK
Notable focus: Full dispute lifecycle from audit to litigation
Contact Information
Website: www.deloitte.com
Phone: +44 (0)20 7936 3000
Address: 1 New Street Square, London, EC4A 3HQ, United Kingdom
LinkedIn: www.linkedin.com/company/deloitte
Facebook: www.facebook.com/deloitteuk
Twitter: x.com/deloitteuk
Instagram: www.instagram.com/deloitte_uk
Resolution Tax
Resolution Tax is a London tax advisory and legal practice focused specifically on disputes, investigations and contentious tax matters. Its litigation service is aimed at situations where a disagreement has reached, or is expected to reach, tribunal proceedings or where prolonged discussions with HMRC have reached an impasse.
The team can develop litigation strategy, prepare correspondence and submissions, manage evidence and disclosure, deal directly with HMRC and represent clients in tax litigation. Its work also extends to judicial review, appeals and tax-related commercial disputes.
Kreston Reeves provides dedicated tax dispute resolution services in London, Kent and Sussex. Its specialists advise individuals and businesses from the first HMRC contact through investigation, negotiation and resolution.
The service covers full and aspect enquiries, COP8 and COP9 investigations, voluntary disclosures, nudge letters, residence and domicile disputes, civil tax fraud cases and appeals. The company also supports Alternative Dispute Resolution and litigation when ordinary correspondence with HMRC does not resolve the issue.
Issues covered: COP8, COP9, residence disputes, penalties and enquiries
Location: London, Kent and Sussex
Notable focus: Dedicated tax dispute specialists and former HMRC inspectors
Contact Information
Website: www.krestonreeves.com
Phone: +44 (0)330 124 1399
Address: 2nd Floor, 168 Shoreditch High Street, London, E1 6RA
LinkedIn: www.linkedin.com/company/kreston-reeves
Twitter: x.com/KrestonReeves
Conclusion
Choosing between tax dispute resolution companies in London depends on the size and structure of the business, its sector, the maturity of its tax processes and the regulatory requirements surrounding the dispute. Some companies provide an integrated service covering tax advisory, investigations, negotiation and litigation, while others concentrate on narrower areas such as HMRC enquiries, serious investigations or tribunal matters. The nature of the dispute and the level of specialist support required should therefore shape the comparison. A suitable partner should provide independent assessment together with practical actions that help control tax risk and strengthen longer-term resilience. This guide is intended to provide neutral context for comparing different approaches and identifying a company that fits the circumstances of the case.
AC
Written by the Acumon team
Acumon is an ICAEW-registered firm of chartered accountants and registered auditors
based in London, with offices in Pitstone, Aylesbury and Bournemouth. Need advice on
anything covered here? Talk to us.
Birmingham businesses and individuals facing an HMRC enquiry, assessment, investigation or appeal can choose from specialist tax consultancies, accountancy firms and legal practices with dedicated…
Dealing with an HMRC enquiry or tax dispute can be challenging, whether it involves a routine compliance check, a voluntary disclosure or a more complex investigation. The right advice can help…
Statutory Sick Pay (SSP) is the minimum an employer must pay an employee who is too ill to work. For 2026/27 it is £123.25 a week or 80% of the employee's average weekly earnings, whichever is…
Read article
Get in Touch
Ready for Accountants Who Move Your Business Forward?
Tell us what you need. Within one business day, a qualified accountant will be in touch to talk it through and give you a clear, fixed-fee quote — no obligation.
We use essential cookies to run this site, plus Google Analytics and Google Ads to
understand how visitors use it and measure our advertising — only with your consent. See our
Privacy Policy.
