Data migration is often treated as a technical workstream. In reality, it is one of the largest sources of business and go-live risk in a transformation. This anonymised scenario-based case study combines recurring delivery conditions observed by Enigma’s senior practitioners across public and private-sector programmes. It does not describe or identify a single client engagement.
The situation
A complex transformation required data to move from legacy systems into a new platform while maintaining interfaces, payroll or financial integrity, operational continuity and a tightly governed cutover sequence. The supplier owned much of the migration tooling and execution, while the client remained accountable for whether the resulting data was fit for business use.
The assurance problem
Migration reporting concentrated heavily on volumes loaded and technical completion. Those measures were necessary but insufficient. Row counts could reconcile while values were wrong, transformation rules could execute successfully while business meaning changed, and technical success could conceal operational exceptions that would only become visible after go-live.
The independent assurance approach
Enigma assessed migration scope, source-to-target mapping, transformation rules, data quality, exception management, control totals, business reconciliation, rehearsal evidence, defect handling, interface dependencies, cutover sequencing, rollback assumptions and ownership of acceptance. Particular attention was paid to whether reconciliation demonstrated business correctness rather than merely technical completeness.
This reflects Enigma’s Data Migration and Cutover Assurance service and the evidence-led approach defined in How We Assure.
What the evidence showed
The programme could demonstrate that migration processes ran, but some evidence did not yet demonstrate that the migrated result was acceptable to the business. Reconciliation controls varied in strength and some exceptions lacked explicit acceptance ownership. Dependencies between migration, interfaces and cutover tasks created additional risk that was not obvious when each workstream was considered separately.
The governance intervention
Migration and cutover readiness were converted into explicit acceptance conditions. Each condition defined the evidence required before progression, the accountable owner and the authority for accepting any residual risk. Rehearsal outcomes were treated as evidence to be analysed rather than milestones to be ticked off.
The treatment aligns with Enigma’s Evidence Sufficiency Standard and Decision Condition Framework.
Why this mattered
The client, not the supplier, ultimately owns the consequence of incorrect live data. Independent assurance creates separation between the team executing migration and the judgement about whether the result is sufficient to support go-live.
The lesson
A successful migration run proves that a process executed. It does not, by itself, prove that the organisation should trust the data. The assurance question is whether the evidence demonstrates completeness, correctness, reconciliation and operational acceptability at the level required for the business decision.