Consolidating 45 entities in 5 days: a OneStream deployment in insurance

Background

A French insurance group with 45 legal entities was running its consolidation process on a patchwork of tools: Oracle Hyperion HFM for statutory consolidation, Excel for IFRS adjustments, a third-party application for intercompany eliminations, and VBA macros for reporting. The quarterly close took 15 business days. Executive leadership set a target of 5.

The Problem

The existing architecture was siloed. Each component operated on its own data model, its own formats, and its own business rules. Manual reconciliations between systems consumed a disproportionate share of the close cycle. Auditors spent more time verifying cross-system consistency than reviewing the numbers themselves.

Three pain points stood out:

No unified audit trail. Every IFRS adjustment required a manual tie-out between HFM and Excel workbooks, with no end-to-end traceability.

High operational risk. VBA macros, maintained by a handful of specialists, created a single point of failure. Losing one key person could stall the entire reporting process.

Inability to meet emerging regulatory demands. IFRS 17 required contract-level granularity that the legacy tooling could not accommodate without a structural overhaul.

The Solution

The group deployed OneStream as a unified platform over an 18-month period. Five previously fragmented processes were consolidated into a single environment:

1. Statutory consolidation
2. IFRS 17 adjustments
3. Intercompany eliminations
4. Regulatory reporting (Solvency II, IFRS 17)
5. Budget planning

OneStream’s Extensible Dimensionality made it possible to handle regulatory granularity (IFRS 17 at the contract level) and management granularity (by line of business) within the same model, without duplicating data.

Risks Identified and How They Were Mitigated

Risk	Potential Impact	Mitigation
Underestimating IFRS 17 complexity	Schedule and budget overrun	Detailed scoping of adjustments with actuarial teams upfront. IFRS 17 workstream ring-fenced in the project plan.
Change resistance from consolidation teams	Low adoption, persistent Excel workarounds	Change management programme launched in month 3. Key users identified per business unit. OneStream certification training.
Over-reliance on the systems integrator	Loss of control post-deployment	Internal OneStream team (3 FTEs) trained in parallel with the rollout. Knowledge transfer written into the contract.
Historical data migration	Reconciliation gaps between old and new systems	Parallel run over two full quarters. Variance thresholds defined and signed off by internal audit.
System unavailability during close periods	Reporting process blocked	Failover environment configured. Business continuity plan tested before the first production close.

Results

Quarterly close timeline: reduced from 15 business days to 5.

Manual reconciliations: down 80%.

Audit effort: reduced by 40% thanks to the built-in audit trail.

Regulatory reporting: Solvency II and IFRS 17 submissions fully automated.

Challenges Encountered

The 18-month deployment exceeded the original 12-month estimate. Two factors drove the delay: the complexity of IFRS 17 adjustments, which required additional iterations with actuarial teams, and the ramp-up of the internal OneStream team, which took longer than planned.

Total project cost exceeded the initial budget by 25%. This overrun was offset within the second year through the elimination of Oracle Hyperion HFM licences, the retirement of third-party tools, and reduced maintenance overhead.

Key Takeaways

This kind of transformation is not a purely technical exercise. Success rests on three pillars: driver-based modelling that reflects how the business actually operates, rigorous ERP integration that guarantees data quality at the source, and change management that brings teams on board from the earliest weeks of the project.

Every context is different, but the patterns recur. Organizations that succeed in EPM migration are the ones that invest as much in governance and people as they do in technology.