SOC 2 vs ISO 27001: Which Do You Need — and Can You Do Both?
Attestation vs certification, Type I vs Type II, three-year certificates vs annual reports — how to choose between SOC 2 and ISO 27001 by market, and how to run them as one program.
Attestation versus certification
SOC 2 and ISO 27001 answer the same buyer question — can we trust you with our data? — in different forms. SOC 2 is an attestation: an independent CPA firm examines your controls against the AICPA Trust Services Criteria and issues a detailed report, typically shared under NDA. ISO 27001 is a certification: an accredited certification body audits your information security management system (ISMS) and issues a certificate anyone can verify. A SOC 2 report describes your controls in depth; an ISO 27001 certificate states that your management system conforms to an international standard.
Type I, Type II and the three-year cycle
SOC 2 comes in two forms. Type I assesses whether controls are suitably designed at a point in time. Type II tests whether they operated effectively over a period, commonly three to twelve months, and is what most enterprise customers ask for. SOC 2 reports cover a past period, so they are renewed annually. ISO 27001 certificates run on a three-year cycle: an initial Stage 1 and Stage 2 certification audit, annual surveillance audits, and recertification in year three.
Which one your market expects
SOC 2 is the default expectation of US enterprise buyers, particularly for SaaS and cloud services. ISO 27001 carries more weight in Europe, the UK, the Middle East, India and Asia-Pacific, and in regulated and public-sector procurement globally. Companies selling into both the US and international markets increasingly need both. The deciding factor is rarely the framework itself — it is what your next ten customers' security questionnaires ask for.
Scope, controls and flexibility
SOC 2 scope is built around the Trust Services Criteria: Security is mandatory, while Availability, Processing Integrity, Confidentiality and Privacy are added based on what you promise customers. ISO 27001 is risk-based: you run a risk assessment, then select controls from Annex A — 93 controls in four themes in the 2022 edition — and justify inclusions and exclusions in a Statement of Applicability. ISO 27001 also certifies the management system around the controls: leadership commitment, internal audit, management review and continual improvement.
Doing both without doing everything twice
The two frameworks overlap heavily — access control, change management, vendor risk, incident response, logging, business continuity. The efficient path is a single ISMS with one control set mapped to both Annex A and the Trust Services Criteria, one evidence repository, and audits sequenced so the ISO surveillance audit and the SOC 2 Type II observation period reuse the same evidence. Note the independence rule: the CPA firm that issues your SOC 2 report cannot also have designed or implemented the controls it examines, which is why readiness and audit are separate engagements.