CAIQ vs SIG: Which Security Questionnaire Should You Use?

When building a vendor risk management program, one of the first decisions you face is which assessment instrument to standardize on. The two most common options — the Cloud Security Alliance's CAIQ and Shared Assessments' SIG — serve different purposes, cover different ground, and fit different vendor populations. Choosing the wrong one does not just waste time; it creates either gaps in your assessments or unnecessary burden on your vendors. Here is how we help clients make this decision.

Both CAIQ and SIG are well-established, widely recognized security questionnaires. Both are used by thousands of organizations for vendor risk assessments. But they were built by different organizations, for different use cases, with different philosophies about what a vendor assessment should cover. Understanding these differences is essential for making an informed choice — or for deciding to use both.

Origins and Governance

CAIQ: Cloud Security Alliance

The Consensus Assessments Initiative Questionnaire (CAIQ) is published and maintained by the Cloud Security Alliance (CSA), a nonprofit organization founded in 2008 with a specific mission: defining and promoting best practices for secure cloud computing. The CSA also maintains the Cloud Controls Matrix (CCM), which is the control framework that CAIQ questions map to.

CAIQ was designed from the ground up for one purpose: evaluating cloud service providers. Every question is oriented around the security concerns specific to cloud-delivered services — shared responsibility models, multi-tenancy isolation, data sovereignty, API security, and virtualization controls.

The CSA also operates the STAR (Security, Trust, Assurance, and Risk) registry, a publicly accessible database where cloud providers can publish their completed CAIQ responses. This transparency mechanism is unique to CAIQ and has no direct equivalent in the SIG ecosystem.

SIG: Shared Assessments

The Standardized Information Gathering (SIG) questionnaire is published by Shared Assessments, a member-driven organization focused on third-party risk management best practices. Shared Assessments was established in 2005 and includes members from financial services, healthcare, insurance, and other regulated industries.

SIG was designed as a comprehensive third-party risk assessment tool — not limited to cloud vendors, but applicable to any vendor relationship. Its scope reflects this broader mandate, covering risk domains that have nothing to do with cloud computing: physical security, human resources security, business continuity, and regulatory compliance, among others.

SIG requires a Shared Assessments membership for access, which involves an annual fee. This contrasts with CAIQ's freely available model.

Scope Comparison

The most important difference between CAIQ and SIG is what they cover. Here is a domain-by-domain comparison:

Risk Domain	CAIQ Coverage	SIG Coverage
Application security	Yes (cloud apps)	Yes (all applications)
Access control and identity	Yes (cloud IAM)	Yes (comprehensive)
Encryption and key management	Yes	Yes
Network security	Yes (cloud networking)	Yes (all network types)
Data security and privacy	Yes (cloud data)	Yes (comprehensive privacy)
Incident management	Yes	Yes
Business continuity / DR	Yes (cloud resilience)	Yes (comprehensive BCP/DR)
Vulnerability management	Yes	Yes
Change management	Yes	Yes
Audit and compliance	Yes	Yes
Physical security	Limited	Yes (detailed)
Human resources security	Limited	Yes (detailed)
Enterprise risk management	Minimal	Yes (detailed)
Regulatory compliance	Cloud-relevant only	Yes (comprehensive)
Server security	Cloud context	Yes (dedicated domain)
Endpoint security	Minimal	Yes (dedicated domain)
Supply chain management	Yes (subprocessors)	Yes (comprehensive)
Cloud hosting services	Yes (deep)	Yes (dedicated domain)

Where CAIQ Goes Deeper

Despite having fewer total questions, CAIQ provides deeper coverage in several cloud-specific areas:

• Multi-tenancy and isolation. CAIQ asks detailed questions about how tenant environments are logically separated, how resources are isolated, and how data commingling is prevented. SIG covers this at a higher level.
• Shared responsibility model. CAIQ explicitly addresses the division of security responsibilities between the cloud provider and the customer. SIG treats this as part of general vendor management.
• Data sovereignty and residency. CAIQ includes specific questions about data location, cross-border transfers, and jurisdictional controls. SIG addresses this under privacy.
• API security. CAIQ asks about API authentication, rate limiting, and access controls in detail. SIG covers API security within application security but less granularly.
• CSA STAR registry integration. Completed CAIQs can be published publicly, enabling buyers to review your responses without sending a questionnaire. This is a workflow advantage, not a content difference, but it is significant.

Where SIG Goes Deeper

SIG's broader scope means it covers several domains that CAIQ either does not address or addresses only superficially:

• Physical security. SIG includes detailed questions about facility access controls, surveillance, environmental protections, and visitor management. For vendors with on-premises components, data centers, or office locations that handle sensitive data, this is critical.
• Human resources security. SIG covers the full HR lifecycle: background checks, security awareness training, termination procedures, and personnel security policies. CAIQ touches on this lightly.
• Enterprise risk management. SIG evaluates the vendor's overall risk management framework, governance structure, and risk appetite. CAIQ focuses on cloud-specific risks.
• Regulatory compliance. SIG asks about compliance with specific regulatory frameworks (HIPAA, PCI DSS, GDPR, SOX) in detail. CAIQ addresses compliance in the context of cloud controls.
• Endpoint device security. SIG has a dedicated domain for endpoint protection, MDM, BYOD policies, and endpoint detection. CAIQ does not address this meaningfully.
• Business continuity. While both cover DR and resilience, SIG's treatment is more comprehensive, addressing business impact analysis, recovery strategies, and testing programs beyond cloud-specific resilience.

Structural Differences

CAIQ Structure

CAIQ v4 organizes questions across 17 control domains that align with the CSA Cloud Controls Matrix (CCM). Each question maps to a specific CCM control objective, creating a direct link between the questionnaire response and the underlying control framework.

Questions are formatted as yes/no with space for explanatory detail. A completed CAIQ can be submitted as a self-assessment to the CSA STAR registry (Level 1) or paired with an independent audit for Level 2 certification.

SIG Structure

SIG organizes questions across 18 risk domains, each with multiple sub-domains. The full SIG contains over 800 questions in an Excel workbook format. Responses typically include a maturity rating, a yes/no/N/A answer, and free-text detail.

SIG also includes risk-based scoping: before completing the full questionnaire, a scoping exercise determines which domains are relevant to the specific vendor relationship. This means that not all 800+ questions are necessarily in scope for every assessment — domains that do not apply can be excluded with documented justification.

Shared Assessments also publishes SIG Lite, an abbreviated version with roughly 200 questions covering the same domains at a higher level. SIG Lite is commonly used for lower-risk vendor assessments.

When to Use Each

Use CAIQ When:

• You are evaluating a cloud or SaaS vendor. CAIQ's cloud-native focus makes it the most efficient instrument for assessing vendors whose services are entirely cloud-delivered.
• Cloud-specific controls are your primary concern. If your risk assessment is focused on data isolation, encryption, API security, and cloud infrastructure controls, CAIQ provides the most targeted coverage.
• You want to leverage the CSA STAR registry. If your organization uses the STAR registry as part of vendor due diligence, CAIQ responses provide a standardized comparison across cloud providers.
• You are a cloud vendor completing assessments. If you are on the receiving end, completing a CAIQ and publishing it on CSA STAR reduces inbound questionnaire volume.
• Budget is a constraint. CAIQ is freely available, while SIG requires a Shared Assessments membership.

Use SIG When:

• You are evaluating vendors beyond cloud/SaaS. Consulting firms, managed service providers, physical service providers, and any vendor with on-premises components require the broader coverage that SIG provides.
• Regulatory compliance is a primary concern. SIG's detailed coverage of regulatory requirements makes it better suited for organizations in heavily regulated industries (financial services, healthcare, insurance).
• You need to assess physical security. If the vendor has physical access to your facilities, handles physical media, or operates their own data centers, SIG's physical security domain is essential.
• You are building a comprehensive TPRM program. SIG's breadth makes it the better foundation for a vendor risk program that needs to cover diverse vendor types. You can always supplement with CAIQ for cloud-specific depth.
• Your auditors or regulators expect it. Some regulatory examiners and auditors specifically look for SIG-based assessments, particularly in financial services.

Use Both When:

Many organizations use both instruments as part of a tiered assessment strategy:

Vendor Type	Assessment Instrument	Rationale
Critical cloud/SaaS (Tier 1)	Full SIG + CAIQ supplement	Comprehensive coverage with cloud-specific depth
Standard cloud/SaaS (Tier 2)	CAIQ	Appropriate cloud-focused assessment
Lower-risk cloud/SaaS (Tier 3)	CAIQ or self-attestation	Lightweight assessment
Critical non-cloud (Tier 1)	Full SIG	Comprehensive coverage including physical, HR, BCP
Standard non-cloud (Tier 2)	SIG Lite	Broad coverage at reduced depth
Lower-risk non-cloud (Tier 3)	Self-attestation	Minimal assessment

Cost and Access Considerations

Factor	CAIQ	SIG
Cost to access	Free	Shared Assessments membership required
Cost to complete (vendor side)	15-25 hours	40-80 hours (full), 10-20 hours (Lite)
Public disclosure option	Yes (CSA STAR)	No
Format	Excel / online	Excel workbook
Update frequency	Aligned with CCM updates	Annual updates
Training / certification	CSA CCSK, CCSP	Shared Assessments CTPRP
Community	CSA chapters, working groups	Shared Assessments member events

Mapping to Compliance Frameworks

Both questionnaires map to established compliance frameworks, but the mappings differ:

CAIQ maps to:

• CSA Cloud Controls Matrix (CCM) — direct alignment
• ISO 27001/27017/27018 — through CCM mappings
• SOC 2 Trust Services Criteria — through CCM mappings
• NIST CSF — through CCM mappings

SIG maps to:

• ISO 27001/27002 — direct question-level mapping
• NIST 800-53 — direct question-level mapping
• SOC 2 Trust Services Criteria — mapped across domains
• HIPAA — mapped within privacy and security domains
• PCI DSS — mapped within relevant domains
• GDPR — mapped within privacy domain

If your organization maintains a SOC 2 report, both CAIQ and SIG responses benefit significantly. A SOC 2 Type II report pre-answers a substantial portion of both questionnaires: roughly 50 to 60 percent of CAIQ questions and 30 to 40 percent of SIG questions can be addressed by referencing your SOC 2 report.

Our Recommendation

In our experience helping clients build vendor risk programs, the most practical approach is:

1. Start with CAIQ if you are a cloud-first organization assessing primarily SaaS and cloud vendors. It is free, focused, and integrates with the CSA STAR ecosystem.

2. Start with SIG if you are in a regulated industry or need to assess diverse vendor types. The membership cost is justified by the breadth and regulatory alignment.

3. Add the second instrument as your program matures. Once your foundational assessment process is running smoothly, layering in the complementary instrument for specific vendor types adds depth without disrupting your existing workflow.

4. Use SIG Lite liberally. For Tier 2 and Tier 3 vendors that need more than a self-attestation but do not warrant a full SIG, SIG Lite provides the right balance.

5. Build your knowledge base around both. Your centralized questionnaire response library should include mappings to both CAIQ and SIG question sets. This allows you to respond efficiently regardless of which instrument a buyer sends.

The choice between CAIQ and SIG is not really a choice between competing standards. They are complementary tools designed for different segments of your vendor portfolio. The best programs use both, applied thoughtfully based on vendor type and risk tier.