When mergers and acquisitions rely on a centralised access review process, onboarding new entities can slow down because every approval flows through the same bottleneck. That delay can obstruct system integration, increase compliance risk, and make it harder to demonstrate timely reviews. A decentralised model lets acquired businesses keep moving while oversight remains aligned to enterprise policy.
Why Centralised Review Becomes a Merger Bottleneck
A centralised user access review process turns due diligence into a queue. In mergers and acquisitions, that queue can become the rate-limiting step for onboarding systems, confirming ownership, and cutting over business users. The practical problem is not just delay, it is that integration teams cannot progress at the pace of the transaction if every access decision waits on one control point.
The bottleneck is usually created by concentration of decision authority rather than by the review activity itself. One team is asked to validate too many entitlements, across too many applications, with too little context on acquired roles, local exceptions, or inherited technical debt. That makes review cycles longer and increases the chance that people begin working before the access picture is fully understood.
When the review process is also used as a gate for segregation of duties, privileged access, or account ownership transfer, the slowdown compounds. The more critical the system, the harder it becomes to approve quickly without either accepting temporary exceptions or holding the integration plan hostage to the review calendar. For broader access governance context, see Ultimate Guide to NHIs — Lifecycle Processes for Managing NHIs and CIS Controls v8.
What the Delay Means for Integration, Audit, and Control
In a transaction, access review are not only an internal security check, they are part of the evidence trail that shows controls were performed on time. If centralised review slows onboarding, the organisation may struggle to demonstrate that new joins, inherited accounts, and access exceptions were reviewed promptly enough to satisfy auditors or regulators. That is especially important where the acquired business brings different naming conventions, role models, or account ownership practices.
The governance risk is that teams may try to compensate with broad temporary access, deferred recertification, or manual spreadsheets outside the normal process. Those workarounds can keep the deal moving, but they also blur accountability and make it harder to prove who approved what, when, and under which policy. A stronger operating model usually separates policy oversight from day-to-day approval routing, so integration can continue while enterprise standards remain intact. A useful reference point is Ultimate Guide to NHIs — Regulatory and Audit Perspectives.
NHIMG’s Ultimate Guide to NHIs highlights the scale of the access-governance problem: only 5.7% of organisations have full visibility into their service accounts. That matters here because merger integration often inherits incomplete inventories, so a central review team can only work as fast as the identity data it receives.
How to Keep Oversight Without Freezing the Deal
What to prioritise: separate approval authority from review coordination. A central policy owner should define standards, but local integration teams need delegated execution for low-risk changes, time-bound exceptions, and account clean-up tasks. That keeps the transaction moving without turning oversight into a single queue.
What to verify: every inherited application should have an owner, a review cadence, and a clear exception path before users are moved into steady-state operations. If those three things do not exist, the review process will keep reappearing later as a blocker rather than a control.
What good looks like: high-risk access still gets central scrutiny, while routine access transitions follow pre-approved patterns with clear evidence of completion. The practitioner test is whether the process reduces uncertainty without stopping integration work that is already low risk and time sensitive.
Practitioner takeaway: the right model is not “centralised versus decentralised” as an absolute choice, it is central policy with distributed execution, so the deal can close and the control can still stand up to audit.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
CIS Controls v8, NIST CSF 2.0, NIST Zero Trust (SP 800-207) and NIST SP 800-63 set the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| CIS Controls v8 | 5 — Account Management | Centralised access review can bottleneck account approval and recertification during M&A. |
| 6 — Access Control Management | M&A onboarding depends on timely access decisions and controlled exceptions. | |
| Recommendation — Delegate routine account review workflows while retaining central approval for high-risk access. Apply least-privilege access control to inherited accounts and time-bound exceptions. | ||
| NIST CSF 2.0 | PR.AC — Access Control | Merged environments need controlled access decisions without blocking integration. |
| GV — Govern | M&A access reviews are a governance issue because oversight and accountability must remain clear. | |
| RS.MA — Mitigation of Vulnerabilities | Process delays can force temporary workarounds that increase exposure during integration. | |
| Recommendation — Align access approval paths to policy so onboarding can proceed without oversharing privileges. Define ownership and decision rights for access reviews across acquired entities. Track and reduce temporary access exceptions before they become standing exposure. | ||
| NIST Zero Trust (SP 800-207) | 3 — Access Enforcement | Centralised review should not become a single enforcement choke point in a zero trust model. |
| Recommendation — Use policy enforcement that evaluates access dynamically instead of routing every decision through one team. | ||
| NIST SP 800-63 | 7 — Identity Lifecycle Management | M&A onboarding changes identity ownership, approval, and review timing. |
| Recommendation — Reconcile identity lifecycle ownership and recertification timing before cutover. | ||
