Why do organisations need IGA if IAM already controls access?

Why This Matters for Security Teams

IAM can grant access, but it does not continuously prove that access still makes sense after a change in role, contract, system ownership, or business process. That is the gap IGA closes. Without governance, access review becomes a box-ticking exercise, and privileged exceptions can linger long after the original need has disappeared. The issue is even sharper for non-human identities, where lifecycle drift is common and visibility is weak.

NHI Management Group research shows that only 5.7% of organisations have full visibility into their service accounts, and 71% of NHIs are not rotated within recommended time frames. That is why IAM alone is not enough for evidence-based control. As the Ultimate Guide to NHIs explains, governance is what keeps identity aligned to operational reality, not just authentication success. The OWASP Non-Human Identity Top 10 also highlights how unmanaged machine access becomes a durable attack path.

In practice, many security teams discover access creep only after a review, incident, or audit has already exposed stale entitlements rather than through intentional lifecycle control.

How It Works in Practice

IGA adds the review, certification, approval, and lifecycle evidence layer on top of IAM. IAM answers whether a user, service account, or application can authenticate and request access. IGA answers whether that access is still appropriate, who approved it, when it should expire, and what proof exists that it was revalidated. For human identities, that usually means joiner-mover-leaver workflows, access recertification, and separation of duties checks. For NHIs, it should also include ownership, purpose, dependency mapping, and secret rotation evidence.

In a mature model, IGA does not replace IAM. It feeds IAM with governed decisions. For example, when a contractor leaves, IGA should trigger revocation of related accounts, API keys, and certificates, while IAM enforces the actual access denial. When a team changes ownership, IGA should require recertification so stale permissions are not inherited by default. That is especially important where secrets live outside a vault, because the Ultimate Guide to NHIs — Key Challenges and Risks documents how quickly unmanaged credentials become persistent exposure.

• Use IGA to define who owns each identity and why it exists.
• Use IAM to enforce authentication and access policy at the point of request.
• Use recertification to confirm access remains justified after role or system changes.
• Use offboarding workflows to revoke accounts, secrets, and downstream entitlements together.

Current guidance suggests that evidence quality matters as much as enforcement quality, because auditors and incident responders need a defensible trail, not just successful logins. These controls tend to break down when identities are spread across multiple clouds and SaaS platforms because ownership and revocation signals become fragmented.

Common Variations and Edge Cases

Tighter governance often increases administrative overhead, so organisations have to balance assurance against workflow friction. The right depth of IGA depends on identity criticality, regulatory exposure, and how fast access changes in the environment. There is no universal standard for this yet, especially for machine identities and ephemeral workloads.

For low-risk applications, lightweight certifications may be enough. For regulated systems, finance workflows, or privileged non-human identities, governance needs to be much stricter. That is where IGA should coordinate with PAM, secrets management, and Zero Trust controls rather than operating as a standalone approval layer. The broader control problem is well documented in the 2024 Non-Human Identity Security Report, which notes that 88.5% of organisations say their non-human IAM practices lag behind or merely match their human IAM efforts. The report also shows that 59.8% see value in dynamic ephemeral credentials, which is a strong signal that governance must account for short-lived access, not only persistent accounts. For related access models, the OWASP guidance on non-human identities remains the clearest public baseline.

Best practice is evolving, but the principle is stable: IAM grants access, while IGA keeps proving that the access is still warranted, owned, and revocable.

Related resources from NHI Mgmt Group

• Why do verified identity and passwordless access still need IAM controls?
• Why does shadow IT increase access risk for IAM and IGA programmes?
• What breaks when an MCP gateway creates a second access path outside existing IAM controls?
• What is the difference between human IAM controls and NHI governance?