We track 18 CPA firms with documented AI, ML, and LLM audit experience. Firms that understand model versioning as change management, training data lineage as access control evidence, and the growing overlap between SOC 2 and ISO/IEC 42001. Engagements start around $15K and run 2 to 12 months depending on scope, observation period, and whether you are pursuing SOC 2 alone or pairing it with ISO 42001 for dual-framework coverage. Every firm listed is a licensed CPA practice subject to AICPA peer review.
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Six picks for the AI audit scenarios buyers actually run: GRC-bundled SOC 2 + ISO 42001, established AI practice for brand-sensitive deals, Vanta-native Series A, Drata-native multi-framework, Bay Area VC-backed AI, and enterprise multi-framework. Each recommendation names one firm with the qualifier that earned the pick.
Thoropass is the pick for an AI startup that wants SOC 2 and ISO 42001 under one CPA engagement. Owns the GRC platform, audits both frameworks, and fixed-fee pricing aimed at under-200-employee AI companies.
Schellman is the pick when buyer scrutiny is high and your AI controls need a brand-name CPA on the cover. Published methodology for AI in SOC 2, Top 50 CPA, with depth in cloud and ML platforms.
Prescient Security is the pick for Series A and growth-stage AI companies on Vanta that want SOC 2 and ISO 42001 in a single engagement. Deep Vanta partner, AI-first portfolio, Slack-based audit communication.
Consilium Labs is the pick for Drata-native AI companies that want a specialist firm explicitly listing AI Companies and ISO 42001 in scope. Multi-framework coverage, 2 to 6 week timelines, fixed-fee pricing.
Sensiba LLP is the pick for VC-backed Bay Area AI companies bundling SOC 2 with ISO 42001 and ISO 27001. B Corp credibility, ISO 42001 for AI governance, and a Bay Area presence that matters for on-site readiness work.
A-LIGN is the pick for enterprise AI vendors selling into regulated industries that need SOC 2 alongside HITRUST, FedRAMP, or ISO. One of the highest-volume US SOC 2 practices runs the framework stack under one engagement.
A generalist auditor will map your MLOps pipeline to generic change-management criteria and miss the controls your enterprise buyers are starting to ask about specifically. AI-experienced firms arrive with test plans built around model versioning, training data access logs, output validation gates, and prompt-injection risks. Not retrofitted from a SaaS template.
Enterprise buyers auditing AI vendors want to know who accessed training data, when, and whether access was authorized and logged. That is a data access control question, but the evidence looks different than traditional application logs. AI-experienced auditors know how to scope training data repositories, evaluate access policies on labeled datasets, and document lineage chains from raw input through model training. A generalist will generate findings or miss coverage entirely.
SOC 2 change management controls require that changes to production systems are authorized, tested, and documented. For AI companies, "production system" includes your deployed model. An auditor who understands ML controls evaluates your model registry, version tagging, approval gates before model promotion, and rollback procedures. The same discipline applied to code deployments, adapted to model deployment workflows. Without this framing, auditors either overscope (treating every training run as a change) or underscope (ignoring model updates entirely).
Enterprise buyers procuring AI-powered products increasingly ask about controls over model outputs: what prevents a model from producing harmful content, leaking sensitive data, or being manipulated through adversarial prompts. OWASP LLM Top 10 provides the taxonomy; your auditor needs to know how to test against it. AI-focused CPA firms map output validation workflows, content filtering, and prompt injection mitigations to SOC 2 Security criteria.
ISO/IEC 42001 (published 2023) is the AI management systems standard that EU procurement and hospital supply chains are beginning to require alongside SOC 2. The frameworks share substantial evidence: governance documentation, risk assessments, access controls, and monitoring logs can satisfy both in a single observation period. Auditors with ISO 42001 certification body accreditation can run both engagements simultaneously, eliminating the cost and calendar drag of two separate processes.
These frameworks are not competitors. SOC 2 establishes your security baseline for US enterprise procurement; ISO 42001 addresses AI governance specifically and carries weight with EU buyers, regulated industries, and organizations responding to the EU AI Act. The question is sequence and scope, not either-or.
| Dimension | SOC 2 | ISO 42001 |
|---|---|---|
| Purpose | Security and availability of systems | AI management system governance |
| Scope | Controls protecting customer data across your environment | AI-specific risk, transparency, and accountability practices |
| Verification | Licensed CPA firm with AICPA peer review | Accredited ISO 42001 certification body |
| Renewal | Annual re-attestation (new Type 2 report each year) | Three-year certification cycle with annual surveillance audits |
| Buyer signal | US enterprise procurement standard | EU buyers, regulated verticals, EU AI Act Article 15 |
| When to choose | Start here; required for most US B2B contracts | Add when EU exposure or AI-specific governance questions appear |
Bottom line: Start with SOC 2 if your buyers are US enterprise and your immediate blocker is a security questionnaire. Add ISO 42001 when EU buyers, hospital procurement teams, or EU AI Act compliance obligations enter the picture, or when a single dual-scope engagement with a qualified firm costs less than two sequential processes.
A SOC 2 report is a formal attestation document issued under AT-C Section 205 by a licensed CPA firm. The issuing firm's name and license appear on the report; AICPA peer review makes that license verifiable. Any vendor that sells AI startups a "SOC 2 report" without a licensed CPA firm's attestation is not selling a SOC 2 report. It is selling a gap assessment or a self-attestation document under a misleading label, and enterprise security reviewers who read SOC 2 reports closely will identify it.
The GRC platform you use to organize your controls is not your auditor; those are different roles, and a vendor that performs both without holding a CPA license is not performing a real audit. Every firm listed on this page is a licensed CPA practice subject to AICPA peer review. That is the floor, not a differentiator.
Sorted by editorial rank based on documented AI, ML, and LLM audit experience, available frameworks, and AICPA-verified CPA standing. For the full auditor list across all industries and verticals, see our complete rankings.
New York, NY
Best For: First-time SOC 2 / ISO 27001 / HIPAA / PCI / HITRUST seekers (under 200 employees) who want one vendor handling both the GRC platform and the audit, eliminating the handoff between Vanta/Drata-style automation and a separate CPA firm. Companies pursuing multiple frameworks who want shared evidence across SOC 2 + ISO 27001 + HITRUST + PCI in a single audit cycle. Mid-market SaaS, fintech, and healthtech seeking 25-50% savings vs. traditional audit firms with fixed pricing.
New York, NY
Best For: B2B SaaS startups (Series A through growth stage) using Drata, Vanta, or Secureframe and prioritizing speed without sacrificing thoroughness. AI/ML companies needing SOC 2 + ISO 42001 together. CSPs pursuing FedRAMP authorization. DoD contractors needing a full C3PAO (newly authorized March 2026). Teams already using Slack who want same-day audit communication.
Tampa, FL
Best For: Defense contractors needing CMMC + FedRAMP, federal agencies requiring top-tier FedRAMP 3PAO, classified systems operators (ONLY auditor with DoD Facility Security Clearance), healthcare organizations needing HITRUST + SOC 2 bundles, companies wanting Top 50 CPA brand with multi-framework expertise
Tampa, FL
Best For: Mid-market to enterprise companies that need multiple compliance frameworks (SOC 2 + ISO 27001 + HITRUST + FedRAMP + PCI) under one roof. CSPs pursuing FedRAMP authorization. Companies that want a top-three FedRAMP 3PAO and #1 SOC 2 issuer on the cover of the report.
Pleasanton, CA
Best For: VC-backed SaaS startups and Bay Area tech companies needing SOC 2 to unlock enterprise sales in 4-8 months. Cloud-native companies already using Drata, Vanta, Secureframe, or Sprinto. Companies combining SOC 2 + ISO 27001 (or SOC 2 + ISO 42001 for AI governance) in a single engagement. APAC-connected companies needing Essential 8, CDR, or GS 007 alongside US compliance. ESG-aware organizations that value B Corp status in their vendor chain.
San Ramon, CA
Best For: Mid-market tech companies ($10M-$500M revenue) prioritizing speed and technology integration. Private equity-backed companies needing bundled audit, tax, and compliance services. Bay Area & West Coast startups wanting local presence and tech industry fluency. Companies expanding internationally requiring both SOC 2 and ISO 27001/27701. Organizations valuing efficiency over brand prestige alone
Los Angeles, CA
Best For: SaaS, FinTech, HealthTech, e-commerce, regulated industries, enterprises to fast-growing startups
Cincinnati, OH
Best For: Companies that want a long-term audit relationship over a transactional, checkbox engagement — and need a firm that can start immediately and cover SOC 2 alongside ISO 27001, ISO 42001, NIST, or HITRUST without bringing in a second vendor.
Kansas City, MO
Best For: Cloud-native SaaS, IaaS, and PaaS companies (high-growth startups through Fortune 1000 enterprises) needing multi-framework attestation (SOC 2 + ISO 27001 + HITRUST + PCI DSS) in a single coordinated engagement. Healthcare technology pursuing HITRUST. Y Combinator-style SaaS startups already running Vanta who want a Vanta MSP partner that can attest. Companies that want boutique-feel partner attention with global-consulting-firm methodology.
Chicago, IL
Best For: Mid-market through enterprise companies needing multi-framework coverage (SOC 2 + FedRAMP, SOC 2 + PCI, SOC 2 + HITRUST). Cloud service providers pursuing FedRAMP authorization (Coalfire is a top-three 3PAO with 121+ FedRAMP assessments). Payment processors needing PCI DSS at Level 1 scale. Healthcare SaaS pursuing HITRUST + HIPAA. DoD contractors needing CMMC Level 2 via Coalfire Federal (operationally independent C3PAO entity).
Chicago, IL
Best For: Healthcare and financial services companies needing data analytics
Denver, CO
Best For: Cloud service providers and SaaS companies seeking SOC 2 Type 2 and ISO certifications with cybersecurity rigor.
USA
Best For: B2B SaaS companies and startups needing rapid SOC 2 compliance for enterprise sales
Toronto
Best For: EdTech companies, AI startups, SaaS providers seeking end-to-end SOC 2 readiness consulting with implementation support
Global
Best For: Global tech companies needing ISO 27001, SOC 2, ISO 42001 (AI), CSA STAR, or combined multi-framework audits via a streamlined Drata-native process
New York, NY
Best For: Highly regulated and technology-focused organizations seeking Big Four-caliber SOC 2 audits with boutique-level partnership and strategic guidance
Lansdowne, VA
Best For: Cloud service providers pursuing FedRAMP combined with SOC 2; DoD contractors needing CMMC; organizations consolidating multiple annual compliance programs
Scottsdale, AZ
Best For: Government contractors and cloud service providers needing specialized FedRAMP, CMMC, and SOC 2 compliance audits with expert advisory.
ISO 42001 overlap, how AI controls are evaluated, LLM provider scope, and SOC 2+ AI add-ons. For SaaS-specific scenarios, see our SaaS directory.
Most AI companies need SOC 2 first. It is the baseline security attestation that US enterprise procurement requires, and it covers the controls your customers are most likely to ask about: access management, encryption, incident response, change management, and monitoring. ISO/IEC 42001 is the AI-specific standard, published in 2023, that addresses AI governance: risk identification for AI systems, transparency obligations, bias monitoring, and accountability structures specific to AI development and deployment. You need ISO 42001 when your buyers operate under EU AI Act obligations, when hospital or regulated-industry procurement teams ask for AI governance evidence specifically, or when your product's AI risk classification triggers governance requirements. For most US-focused AI startups closing their first enterprise contracts, SOC 2 unblocks the deal. ISO 42001 becomes relevant at growth stage when regulated verticals or European buyers are in the pipeline. Some CPA firms with ISO 42001 certification body accreditation can run both in a single engagement, which changes the economics: one observation period, shared evidence, one set of auditor fees.
AI-experienced auditors map ML-specific practices to the existing Trust Service Criteria rather than inventing new categories. Model versioning and deployment workflows are evaluated as change management controls: is model promotion to production authorized, tested, and logged? Training data access logs are evaluated as logical access controls: who can read, modify, or export training datasets, and are those permissions consistent with your documented access policies? Output validation pipelines and content filtering are evaluated under the Security criterion's monitoring and anomaly detection requirements. Prompt injection mitigations may be evaluated against OWASP LLM Top 10 as a reference framework. The auditor samples evidence across your observation period: model registry entries, deployment approval records, data access logs, incident tickets, and tests whether your controls operated consistently, not just whether they exist. A generalist auditor may not know which evidence to request or how to evaluate a model registry against change management criteria. That gap produces findings that specialist firms avoid.
Yes, if the CPA firm is also an accredited ISO 42001 certification body. These are distinct credentials: a CPA license and AICPA peer review are required to issue a SOC 2 report; ISO 42001 certification body accreditation is required to issue an ISO 42001 certificate. Some firms hold both. When they do, a dual-scope engagement uses one observation period and one set of fieldwork interviews, with evidence mapped to both frameworks simultaneously. Controls that satisfy SOC 2's Security criterion (access controls, risk assessments, monitoring procedures) overlap substantially with ISO 42001's AI governance requirements. The shared evidence base is what makes dual-scope engagements economical: you are not running two audits sequentially, you are running one engagement that produces two outputs. Not every firm on this list offers ISO 42001 certification; those that do are identified in their individual profiles. Confirm accreditation before assuming a firm can deliver both.
No. OpenAI, Anthropic, Google, and other LLM providers publish SOC 2 reports that cover their infrastructure and services. Those reports cover what they are responsible for: the model serving infrastructure, the API endpoints, and the data they process within their systems. They do not cover your application layer. Your prompt handling, system prompts, context injection, output parsing, customer data passed to the API, and the downstream logic that acts on model outputs are all in your scope, not theirs. The same principle applies to vector databases, ML observability platforms, and any AI infrastructure vendor you use. Each vendor's SOC 2 report covers their service boundary. Your SOC 2 audit covers how you built on top of those services, how customer data flows through your application, and whether your controls over that data are operating effectively. Enterprise buyers understand this; they will ask for your report separately from your subprocessors' reports.
SOC 2+ refers to a SOC 2 report that includes additional criteria beyond the standard Trust Service Criteria. The AICPA has published supplemental AI criteria that can be layered onto a base SOC 2 engagement, covering AI-specific controls around transparency, bias monitoring, model governance, and responsible AI practices. A SOC 2+ AI report is useful when a buyer wants AI governance evidence in the format they already know how to evaluate (SOC 2) but ISO 42001 is premature or not required. It is more lightweight than dual-scope ISO 42001 certification and does not require a separate certification body. You need it when enterprise buyers are asking AI-specific security questions that your base SOC 2 report does not address and you are not ready to pursue ISO 42001. It is not a substitute for ISO 42001 when EU AI Act compliance or formal AI management system certification is the actual requirement. Ask your auditor whether they offer SOC 2+ AI criteria as an add-on to your existing scope.
AI-first SaaS still has to handle multi-tenant data isolation, Availability TSC, and subprocessor scope. See SaaS-experienced firms.
ISO 42001, ISO 27001, HITRUST, FedRAMP. When to add each one, how they map to SOC 2, and which auditors handle them.
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