TL;DR: Access tokens and ID tokens serve different security functions, and Descope’s explainer shows why teams still confuse authorization, authentication, and session handling in token-based systems. The practical issue is not token terminology but control design, because the wrong token type in the wrong flow weakens IAM boundaries and increases exposure.
At a glance
What this is: This is an IAM explainer on the difference between access tokens and ID tokens, showing that the security risk comes from using the wrong token for the wrong trust decision.
Why it matters: IAM teams need this distinction because token confusion creates authentication and authorization boundary errors that can affect human, machine, and delegated access flows.
By the numbers:
- Microsoft access tokens are assigned random lifespans by default, ranging from 60 to 90 minutes and averaging 75 minutes.
Context
Access token and ID token confusion is a governance problem because the two tokens answer different trust questions. An access token is for authorization, while an ID token is for authentication, and treating them as interchangeable blurs the boundary between who a subject is and what it can do. In IAM terms, that confusion can leak into API access design, session handling, and federated application flows.
The article is useful because it frames token handling as a control design issue rather than a terminology issue. That matters across IAM programmes because token misuse can affect human sign-in flows, delegated application access, and the lifecycle of token-based sessions. The practical question is not whether a system uses JWTs, but whether the token type matches the decision the system is making.
Key questions
Q: How should IAM teams separate access tokens from ID tokens in application design?
A: Treat access tokens as authorization artefacts and ID tokens as authentication assertions. Build application flows so APIs consume access tokens for scope checks, while client applications use ID tokens only to confirm identity. That separation reduces boundary confusion and makes validation rules easier to enforce consistently.
Q: When do token lifetimes become a security problem rather than a usability choice?
A: Token lifetimes become a security problem when they outlast the trust decision they represent or remain valid in systems that were never intended to accept them. Short-lived access tokens reduce exposure, but only if expiry, audience, and issuer checks are enforced at each consuming service.
Q: What breaks when refresh token rotation does not include reuse detection?
A: Rotation without reuse detection only shortens exposure on paper. A stolen old token can still be replayed until the server notices, which means the organisation has no reliable signal that compromise occurred. Reuse detection turns a stale token presentation into a revocation event.
Q: Why do token handling mistakes matter for API and client trust boundaries?
A: Because token semantics define where trust is allowed to travel. If a client accepts a token type it should not trust, or an API authorizes requests without checking purpose and audience, the identity provider stops being the source of control and becomes only a token issuer.
Technical breakdown
Access tokens vs ID tokens in OAuth 2.0 and OIDC
Access tokens are used to grant access to protected resources, usually by carrying scopes or permissions that an API can evaluate. ID tokens are used to assert identity to a client application, usually after authentication via OpenID Connect. The two often arrive in the same login flow, which is why teams confuse them, but the decision points are different: one authorises a request, the other communicates who authenticated. In practice, this distinction shapes how applications trust the token and where validation must occur.
Practical implication: keep authorization decisions tied to access tokens and identity assertions tied to ID tokens.
JWT claims, token lifetime, and session boundary design
The token payload matters because claims such as iss, sub, aud, exp, iat, and amr describe issuer, subject, audience, lifetime, and authentication context. Access tokens often have shorter, configurable lifespans, while ID tokens may track the user session more closely. That difference changes risk: a token that lives too long or is accepted outside its intended audience can outlast the trust decision it was meant to represent. Session boundary design therefore has to account for token purpose as well as expiry.
Practical implication: validate audience, expiry, and token purpose separately instead of relying on JWT format alone.
Refresh tokens and why they extend trust differently
Refresh tokens are not replacements for access or ID tokens. They are a mechanism for obtaining new access tokens without re-prompting the user, which reduces friction but also extends the trust relationship over time. That makes refresh token handling a lifecycle control problem, because rotation, revocation, and secure storage determine how far a compromise can propagate. If refresh tokens are treated as ordinary session data, the system silently lengthens the exposure window.
Practical implication: treat refresh token rotation and revocation as governance controls, not convenience features.
NHI Mgmt Group analysis
Token confusion is really trust confusion. The article shows that access tokens and ID tokens are not interchangeable artefacts but different trust instruments. When teams collapse authentication and authorization into one token-handling pattern, they weaken the policy boundary that IAM is supposed to enforce. The implication is that token type selection must be governed as a design decision, not left to implementation habit.
Session duration is part of identity risk, not just user experience. The lifespan of a token determines how long a trust decision remains active, and that makes expiry and rotation central to IAM control design. Short-lived access tokens reduce exposure, but only if they are accepted only where their audience and purpose are valid. Practitioners should treat lifetime as a governance attribute, not a formatting detail.
Refresh tokens create lifecycle debt when rotation and revocation are weak. Extending access through refresh tokens can improve usability, but it also increases the number of control points that must be managed. If refresh tokens are stored, reused, or rotated poorly, the trust relationship persists beyond the original authentication event. That makes lifecycle discipline the difference between controlled continuity and silent access extension.
Identity boundaries matter across human, application, and delegated access. The same token confusion that hurts consumer or workforce sign-in can also distort machine-to-machine and federated access flows. IAM teams should not treat token semantics as a front-end concern only, because the downstream effect is often policy drift between the application, API, and identity provider. The practitioner conclusion is to govern token purpose at the architecture level.
From our research library:
- AI-related credential leaks surged 81.5% year-over-year in 2025, with the surrounding AI infrastructure leaking 5x faster than core LLM providers, according to the State of Secrets Sprawl 2026.
- Read next: AI Agent Authorisation Guide
What this signals
Token semantics should be treated as an identity architecture issue, not a developer convenience. Teams that accept whatever token happens to be available tend to blur authentication, authorization, and session extension into one control path, which makes governance harder across applications and APIs.
Trust boundary precision: The most durable design pattern is to bind each token type to one decision only. That means validating purpose, audience, and expiry before the token reaches application logic, rather than assuming the token format itself is enough.
For practitioners
- Separate authentication from authorization in design reviews Map each flow to the specific token it should consume, and reject designs that use an ID token to authorise API access or an access token to prove user identity.
- Validate token audience and expiry in every consuming app Check aud, exp, iss, and token purpose before the token reaches business logic, especially where multiple apps or APIs trust the same identity provider.
- Treat refresh token rotation as a lifecycle control Use rotation, revocation, and secure storage to prevent long-lived session extension from becoming an undetected persistence mechanism.
- Document token handling patterns for APIs and clients Define which token each application class can accept, how long it may remain valid, and what should happen when the token no longer matches the intended audience.
Key takeaways
- Access tokens and ID tokens solve different control problems, and IAM teams should not let them become interchangeable in application design.
- The real security issue is boundary drift, where a token is accepted for a purpose it was never issued to support.
- Refresh token governance matters because rotation and revocation determine whether extended access stays controlled or turns into persistence.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
NIST SP 800-63, NIST CSF 2.0, NIST SP 800-53 Rev 5 and OWASP ASVS set the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| NIST SP 800-63 | SP 800-63C — Federation | OIDC token handling sits in the federation layer where identity assertions are consumed. |
| Recommendation — Apply SP 800-63C to govern token federation boundaries and restrict where identity assertions are accepted. | ||
| NIST CSF 2.0 | PR.AA-05 — Access Permissions, Entitlements and Authorizations | Access tokens carry authorization decisions that must match intended permissions and entitlements. |
| Recommendation — Use PR.AA-05 to align token-based access decisions with explicit permissions and authorizations. | ||
| NIST SP 800-53 Rev 5 | IA-5 — Authenticator Management | Token lifetimes, rotation, and revocation are authenticator lifecycle controls. |
| Recommendation — Apply IA-5 to enforce token rotation, expiration, and revocation discipline. | ||
| OWASP ASVS | V10 — OAuth and OIDC | The article is specifically about how OAuth 2.0 and OIDC token types differ in practice. |
| Recommendation — Review V10 to ensure your OAuth and OIDC token handling matches token purpose and trust boundaries. | ||
Key terms
- OAuth Token: A short-lived access credential issued by an OAuth 2.0 authorisation server granting an NHI scoped access to specific resources for a defined period. Preferred over static API keys because their short lifetime limits the exploitation window if intercepted.
- Identity Token: A persistent, privacy-preserving reference that represents a person or account without exposing the original sensitive attribute. In practice, it lets systems recognise continuity across channels while keeping raw data out of downstream workflows and reducing the blast radius of identity exposure.
- Refresh Token: A longer-lived credential that can mint new access tokens without forcing the user to authenticate again. Because refresh tokens can preserve access for extended periods, they are a major governance concern when malicious or over-scoped applications are granted consent.
Deepen your knowledge
NHI governance, agentic AI identity, and machine identity lifecycle are core topics in our NHI Foundation Level course, the industry's only accredited NHI security programme. If you are responsible for identity security strategy or NHI governance in your organisation, it is worth exploring.
Published by the NHIMG editorial team on August 19, 2026.
Updated on October 6, 2026.
NHI Mgmt Group, the independent authority on Non-Human Identity, IAM, and Agentic AI security. nhimg.org