Operational guidance, not legal advice. This page distills named public sources (regulator guidance and industry practice). It is not a legal determination, not a notification decision, and not a substitute for your counsel, insurer, or a retained DFIR firm. Verify applicability and current deadlines for your facts and jurisdiction.
How do you choose a security auditor?
Last verifiedHow do you choose a security auditor? Walk the decision tree: outcome, provider type, required accreditation, then shortlist. Not legal advice. Not procurement advice. Does not determine which standard applies to YOU.
Security assurance guidance, last verified 10 September 2026 against AICPA attestation standards, ISO/IEC 27001:2022, ISO/IEC 17021-1:2015, ISO/IEC 42001:2023, PCI SSC QSA programme materials, FedRAMP 3PAO requirements, and HITRUST assessor programme materials. This page does not determine that any standard applies to YOU and does not start a clock.
Decision tree — outcome → provider type → accreditation → shortlist
Start with the deliverable YOUR customer or regulator names in writing — not the logo they mentioned in a sales call. This page does not determine that a standard applies to YOU. Last verified 10 September 2026. Not legal advice.
| Step | Question | If yes → | Kind of text |
|---|---|---|---|
| 1 | What output do YOU need? | SOC 2 report → licensed CPA firm. ISO/IEC 27001 certificate → accredited CB. PCI ROC → QSA. FedRAMP ATO package → 3PAO. HITRUST → HITRUST assessor. | Best practice — match contract to instrument. |
| 2 | Which provider type can issue it? | CPA attestation, accredited certification, QSA validation, 3PAO assessment, or HITRUST assessment — not a generic consultant letter. | Professional standard per scheme. |
| 3 | What accreditation is required? | AICPA peer review + CPA licence; ISO/IEC 17021-1 via national AB + IAF MLA; PCI SSC QSA listing; FedRAMP/A2LA 3PAO; HITRUST assessor listing. | Professional standard — verify on registers. |
| 4 | Shortlist and verify | Use stated criteria pages on this site; print the question bank; verify registers before signing. | Best practice — ShipReadyMetrics recommendation. |
Provider types by framework
| Framework / outcome | Provider type | Accreditation / authorization | Register to check |
|---|---|---|---|
| SOC 2 Type I / II | Licensed CPA firm | AICPA SSAE 18 / AT-C; AICPA peer review; ET §1.200 independence | AICPA peer-review roster; state CPA board |
| ISO/IEC 27001 certificate | Accredited certification body | ISO/IEC 17021-1 via national AB; IAF MLA | IAF CertSearch; UKAS / ANAB / DAkkS |
| ISO/IEC 42001 certificate | Accredited certification body | ISO/IEC 17021-1 for ISO/IEC 42001 scope | IAF CertSearch — ISO 42001 docs hub on this site |
| PCI DSS ROC | Qualified Security Assessor (QSA) | PCI SSC QSA listing | PCI SSC QSA directory |
| FedRAMP authorization | Third-party assessment organization (3PAO) | FedRAMP / A2LA 3PAO recognition | FedRAMP marketplace; A2LA |
| HITRUST CSF | HITRUST assessor | HITRUST assessor programme listing | HITRUST MyCSF assessor list |
What to do now
- Write down the exact deliverable name from YOUR contract or RFP.
- Match it to one row in the provider-type table — if none match, ask counsel what instrument is actually required.
- Open the relevant register before shortlisting any firm.
- Use the best SOC 2 audit firms or best ISO 27001 certification bodies pages for named shortlists — not rankings.
- Print the questions-before-hiring-an-auditor guide before calls.
Checklist
- Deliverable named in writing (SOC 2, ISO 27001, PCI ROC, etc.)?
- Provider type can legally/professionally issue that deliverable?
- Accreditation verified on current public register?
- Independence clear — preparation and audit separated?
- Timeline, scope, and fees documented before signing?
Where this shows up in ShipReady Metrics
The 24-framework crosswalk maps evidence to canonical controls with a crosswalk-density honesty layer. One readiness posture can feed whichever accredited auditor applies — ShipReadyMetrics does not pick the auditor, does not issue attestations or certificates, and is not legal advice.