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A full assurance practice, under one partnership

Audit, controls, corporate tax and compliance — the disciplines that keep your numbers defensible, delivered with consistency from one accountable partner.

Our Disciplines

Find the engagement you need

Audit

Statutory Audit

Independent audit of company and group financial statements under UK GAAP and IFRS, with a clear opinion and a candid management letter.

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Audit

Group & Consolidated Audit

Coordinated component audits across subsidiaries and jurisdictions, intercompany eliminations and a single coherent group opinion.

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Tax

Corporation Tax Compliance

Accurate CT600 preparation, computations and disclosures filed on time, with full audit-ready supporting workings.

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Tax

R&D Tax Relief

Robust R&D claims under the merged scheme — technical narratives and cost analyses built to withstand HMRC enquiry.

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Risk

Internal Controls & SOX

Design, document and test the controls that protect your business, with practical remediation plans and SOX readiness.

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Risk

Risk Assurance

Independent assurance over operational, financial and regulatory risk — giving your audit committee evidence it can rely on.

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Advisory

Transaction & IPO Readiness

Historical financial information, working-capital reports and the assurance investors and the LSE demand pre-listing.

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Advisory

Due Diligence

Buy-side and sell-side financial due diligence that surfaces the issues before they become deal-breakers.

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Advisory

ESG & Non-Financial Reporting

Assurance over sustainability and non-financial disclosures, aligned to evolving CSRD and TCFD expectations.

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Cornerstone audit specialists reviewing controls documentation together
How We Engage

One partner. One file. One standard.

Every Cornerstone engagement is led by a named partner who stays with you from scoping to sign-off. No anonymous teams, no quality drift between years — just a consistent, accountable relationship.

  • Fixed timelines

    An agreed plan with milestones, so year-end never becomes a scramble.

  • Transparent fees

    Clear scope and a fixed fee wherever possible — no opaque hourly surprises.

  • Year-round access

    Your partner is available between audits, not just at sign-off.

Engagement Pricing

Transparent fees, scaled to complexity

Indicative annual fees for recurring engagements. Every quote is tailored after a no-obligation scoping conversation.

Foundation
£6,500
from, per annum

For owner-managed and growing companies needing a first statutory audit and clean compliance.

  • Single-entity statutory audit
  • Corporation tax return
  • Management letter
  • Named audit partner
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Most Chosen
Corporate
£18,500
from, per annum

For established and scaling businesses requiring deeper assurance, tax planning and controls work.

  • Multi-entity statutory audit
  • Corporate tax & R&D claims
  • Internal controls review
  • Quarterly partner check-ins
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Enterprise
Bespoke
tailored engagement

For listed groups, regulated entities and transactions requiring the full breadth of our practice.

  • Group & consolidated audit
  • IPO & transaction support
  • Dedicated engagement team
  • Audit-committee reporting
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Common Questions

What boards ask us first

A UK company generally requires an audit once it exceeds two of three thresholds — turnover above £10.2m, gross assets above £5.1m, or more than 50 employees — though many companies elect for an audit earlier to support lenders, investors or a future transaction.

For a single entity, fieldwork typically runs two to three weeks, with sign-off four to six weeks after your year-end accounts are ready. Group audits take longer. We agree a fixed timeline at scoping so there are no surprises.

Yes, within the independence rules that govern auditors. We maintain strict safeguards and decline any work that would compromise our objectivity. For listed and PIE clients, certain non-audit services are restricted and we will advise you accordingly.

Not at all. Changing auditor is a straightforward, well-trodden process. We handle the professional clearance with your outgoing firm and the Companies House formalities, and ensure continuity so nothing is missed in the transition.

Frequently. We audit UK subsidiaries of international groups, reporting to overseas auditors and reporting packs under both IFRS and US GAAP reconciliations where required.

Next Step

Let's scope your engagement

A short conversation tells us what you need and what it should cost. No obligation, no jargon.

Request a Proposal → Speak to a Partner