ISO 27001 vs SOC2: Which Do You Need?

If you sell mainly in the UK or Europe, people ask for ISO 27001. If you sell to US tech, SaaS or enterprise customers, they often ask for SOC 2. Increasingly, UK firms are being asked for both SOC 2 and ISO 27001, with many organizations now pursuing both SOC frameworks to benefit from their complementary strengths and overlapping requirements. Adoptech+2Assent Risk Management+2

This guide explains the difference, the overlap, and how to use ISO 27001 as the base for SOC 2.

What is the ISO 27001 information security management system?

ISO/IEC 27001:2022 is an international standard for building and maintaining an Information Security Management System (ISMS). It is risk based, certifiable by a UKAS-accredited body, and widely recognised by UK buyers, government suppliers and EU customers. To maintain ISO 27001 certification, organisations must undergo ongoing surveillance audits, which are conducted annually between recertification cycles to ensure continued compliance and effectiveness. iso.org +1

You get: a formal certification issued by an accredited certification body, which is globally recognized. This differs from SOC 2, which provides a formal attestation report but not a certification.

What is SOC 2?

SOC 2 is an American attestation standard from the AICPA (American Institute of Certified Public Accountants). An independent, licensed CPA firm and certified public accountant reports on how well your controls meet the five Trust Services Criteria (security, and optionally availability, processing integrity, confidentiality, privacy), which form the basis of the audit. For SOC 2 Type II reports, the assessment covers the design and operating effectiveness of controls over a specified period. Customers can request the report and review the details. aicpa-cima.com +2Secureframe+2

You get: a SOC 2 report (Type I or Type II), not a certificate.

Key differences (at a glance)

ISO 27001 vs SOC 2: Which Does Your SaaS Need?

Both demonstrate security credibility — but they serve different markets and have different scopes. Many SaaS companies end up pursuing both.

ISO 27001

Overlap

SOC 2

Recognition & Origin

International standard (ISO/IEC). Recognised globally — especially strong in Europe, UK, Middle East, APAC, and enterprise procurement.

Both widely accepted

US-based framework (AICPA). Dominant in North America — US enterprise buyers and investors typically ask for this first.

Scope

Covers your entire Information Security Management System — people, processes, and technology across your whole organisation.

–

Scoped to specific Trust Services Criteria: Security (required), plus optional Availability, Confidentiality, Privacy, Processing Integrity.

What You Get

An accredited certificate from a UKAS (or equivalent) accredited certification body. Publicly verifiable. Lasts 3 years with annual surveillance audits.

Both involve third-party audit

A SOC 2 Type I (point-in-time) or Type II (6–12 month period) report. Not a certificate — a report shared with customers under NDA.

Audit Approach

Risk-based. You design controls appropriate to your risks. Auditor checks your ISMS is fit for purpose and controls are operating effectively.

Both test control effectiveness

Criteria-based. Auditor tests against defined Trust Services Criteria. Less flexibility — controls are more prescribed.

Typical Cost & Timeline

£8,000–£20,000 certification cost. 6–12 months to prepare from scratch. Annual surveillance audits required.

–

$15,000–$50,000+ (Type II). 6–12 months for Type II period. Annual renewal required.

Choose ISO 27001 if you’re…

Selling into European or UK enterprise markets
Responding to public sector or government tenders
Building a long-term security management programme
Required by a customer contract to hold a certificate
Looking for a globally recognised, verifiable credential

Choose SOC 2 if you’re…

Primarily selling to US enterprise or mid-market customers
Going through US VC due diligence processes
Responding to US security questionnaires
Operating in a sector where SOC 2 is the default expectation
Needing a report quickly for a specific customer deal

The good news: ISO 27001 and SOC 2 share significant overlap in controls. If you build your ISMS to ISO 27001 standard first, achieving SOC 2 becomes considerably faster and cheaper — most of the hard work is already done.

Area	ISO 27001	SOC 2
Origin	International / ISO	US / AICPA
Output	Certificate (e.g. UKAS)	Attestation report (Type I / II)
Focus	Management system with defined audit scope, plus Annex A controls. Emphasizes establishing a control environment tailored to organizational needs and integrating various compliance criteria.	Operating effectiveness of controls within the audit scope, measured against the Trust Services Criteria (TSC). The control environment is assessed for suitability and effectiveness in meeting TSC requirements.
Recognition in UK	Very high (public sector, larger buyers)	Growing, mainly for US-facing work Adoptech+1
Typical driver	Tenders, supplier due diligence, NHS/finance supply chains	US enterprise / SaaS customers, security questionnaires
Renewal	Annual surveillance audits, recertification every 3 years	Annual examination (Type II)

Similarities

Both expect strong access control, change, incident, supplier and asset management. Both frameworks require many of the same security controls and are recognized as leading security standards. ISO 27001 puts this in Annex A; SOC 2 in the Common Criteria. IT Governance+1
Both rely on policies, evidence and being able to show you follow your own processes. Both frameworks require robust internal controls and security practices as part of their compliance.
Both are accepted by security-mature customers as proof you take data protection seriously. Both standards help organizations protect customer data and customers data, and implementing information security best practices and security controls is essential for building trust. Proton’s move to hold ISO 27001 and SOC 2 together is a good current example. TechRadar+1
Both ISO 27001 and SOC 2 emphasize the importance of customer data protection through comprehensive security controls.

Where ISO 27001 works best (UK view)

Choose ISO 27001 first if you:

Sell mainly in the UK/EU
Need something procurement understands (especially if they ask for “UKAS-accredited 27001”)
Want a single, risk-based framework that you can grow over time—ISO 27001 serves as a robust compliance framework that helps organizations meet regulatory requirements and achieve regulatory compliance
Need to show GDPR-friendly governance as well as security

ISO 27001 includes comprehensive requirements for information security, covering business continuity planning and the management of information security risks.

That is the most common route for UK companies, adding SOC 2 only when the US market demands it. ISO 27001 provides a structured approach for managing information security in line with international standards. Adoptech+1

When SOC 2 is the better first move

Pick SOC 2 first if you:

Are a UK SaaS selling mostly to US customers, especially as a service organization seeking to demonstrate compliance with US standards
Keep getting 200-line US security questionnaires
Are integrating into US tech/fintech supply chains and they specifically name “SOC 2 Type II” for service organizations

SOC 2 speaks the customer’s language in that market and helps organizations demonstrate security compliance, meet security objectives, and strengthen their security posture in the eyes of US customers. Achieving SOC 2 can enhance the organization’s security posture and build trust with US clients. Assent Risk Management+1

Decision table

Your situation	Go for	Notes
UK/EU customers, bids, frameworks	ISO 27001	UKAS badge carries weight. Organisations can achieve certification through the ISO 27001 process.
UK company expanding into US SaaS	ISO 27001 → SOC 2	Build ISMS first, map to TSC. Pursuing both ISO 27001 and SOC 2 can provide comprehensive coverage.
Already ISO 27001, US prospect now asks “SOC 2 Type II?”	Add SOC 2	Reuse Annex A controls as evidence. Organizations can benefit from aligning SOC 2 and ISO frameworks.
US parent, UK subsidiary delivering service	SOC 2 (group) + local 27001	Shows global and local assurance.
Need something marketing can show on site	ISO 27001	Public certificate easier to reference. Organizations can achieve certification through the ISO 27001 process.
Customer wants to see control detail (logs, HR checks, vendors)	SOC 2	Report is more granular IT Governance

These two frameworks help organizations achieve compliance with both international and US standards.

Using ISO 27001 as the foundation for SOC 2

Achieving ISO 27001 and SOC 2 compliance involves a comprehensive compliance process that covers the entire process from initial planning, gap analysis, and implementation to ongoing monitoring, external audits, and continual improvement. Both standards require structured steps to ensure robust information security and ongoing adherence to requirements.

This is the route I recommend for most UK firms:

Implement ISO 27001 – scope, risk assessment, Statement of Applicability, Annex A controls. As part of the initial certification audit and certification process, conduct a gap analysis to identify areas needing improvement before formal audits. That gives you structured policies, asset registers, incident, supplier, access, backups. iso.org +1
Map controls to SOC 2 TSC – security/common criteria will map directly (access, change, logging, incident, vendor); availability/confidentiality may need extra evidence. When mapping controls and evidence, focus on how your organization’s ISMS is designed to protect sensitive information and safeguard data, ensuring all relevant controls are in place and effective. Secureframe+1
Tighten monitoring and evidence cadence – SOC 2 Type II wants to see that you operated the control over a period; ISO 27001 is happier with periodic checks. For both frameworks, ongoing monitoring, continuous monitoring, and ongoing compliance are essential to regularly assess control effectiveness, identify vulnerabilities, and ensure adherence to security policies.
Engage a UK firm that can deliver SOC 2 examinations – there are now several in the UK precisely because demand from US buyers has gone up. Assent Risk Management

External audits and external audits are critical in the certification and attestation processes for both ISO 27001 and SOC 2, providing independent validation of your controls and compliance status.

Because ISO 27001 already gives you an ISMS, it reduces SOC 2 effort later — this is exactly why companies like Proton run them side by side. TechRadar+1

Compliance automation and the use of a compliance automation platform can significantly streamline the audit process, reduce manual effort, and help maintain control effectiveness. These tools support ongoing compliance activities, accelerate audit readiness, and make it easier to manage evidence collection and documentation throughout the certification process.

So, which should you choose?

Primarily UK/EU, tenders, professional services: start with ISO 27001.
Primarily US SaaS/tech customers: do SOC 2, or 27001 now and SOC 2 within 12 months.
Mixed market or aiming to look like a serious security vendor: do 27001 first, then add SOC 2.

If you tell me your sector and who’s actually asking (UK buyers, US platform, finance, NHS), I can tailor the decision table to that.