Single Source of Truth
Single Source of Truth (SSoT) is the data-governance principle that every data concept — a customer, a product, a financial transaction — has exactly one authoritative system that owns it. Other systems may have copies for operational reasons, but those copies derive from the SSoT and must align with it on conflict. For ERP-centric architectures, SSoT is the conceptual foundation for master-data management, integration architecture and reporting consistency.
Why SSoT matters
Without an SSoT discipline, every business concept exists in multiple variants across systems — with subtle differences that compound into operational and reporting confusion. A customer with three slightly different addresses in CRM, ERP and shipping system generates failed deliveries. A product with different weight values in PIM and ERP causes shipping-cost errors. A financial transaction posted differently in operational ERP and financial reporting tool creates reconciliation nightmares. SSoT eliminates these by defining: who owns the data, who reads from whom, what happens on discrepancies. The discipline is governance more than technology — many SSoT failures come from organisations where everyone believed they were the owner.
Typical data-ownership assignments
- Customer master: typically CRM owns (lead-to-customer lifecycle) with ERP as receiver of billing-ready customer data
- Supplier master: ERP usually owns (commercial transaction-centric) with supplier-portal systems as readers
- Product master: PIM owns descriptive data, ERP owns commercial-and-inventory data, each as authoritative for its scope
- Employee master: HCM owns personal and organisational data, ERP owns cost-centre assignment and time-and-attendance integration
- Financial transactions: ERP owns the journal, with BI tools and consolidation systems as downstream consumers
- Inventory: ERP usually owns; WMS may have operational primacy with ERP as eventually-consistent receiver
- Orders: source-system-specific — shop owns e-commerce orders, ERP owns B2B sales orders
Realistic SSoT versus federated truth
Pure SSoT is rare in practice. Most organisations operate with federated truth: different systems own different aspects of the same business concept, with explicit integration patterns reconciling them. Customer data is co-owned by CRM (relationship) and ERP (commercial), with sync rules defining who wins on which field. Product data is co-owned by PIM (marketing) and ERP (commercial). Federated truth is more pragmatic but requires explicit conflict-resolution rules: (1) Authoritative-field assignment — for each field, designate the system that wins on conflict. (2) Audit-trail of changes — track who changed what and when, allowing investigation when discrepancies arise. (3) Reconciliation reports — periodic comparisons that surface drift.
Implementing SSoT discipline
Four practical steps. (1) Map the data landscape: list every system holding key business data and the concepts each holds. Often surprising in scope — large organisations typically discover 10-20 systems holding customer data alone. (2) Assign ownership: for each data concept, designate the authoritative system. Document the decision in a data-ownership matrix accessible to all stakeholders. (3) Define integration patterns: how data flows from owner to consumers, with cadence (real-time, hourly, daily), conflict resolution rules and exception handling. (4) Govern continuously: data-ownership decisions drift as new systems appear and responsibilities change. Quarterly reviews of the data-ownership matrix prevent gradual erosion. Mid-market operations achieving this discipline consistently report cleaner reporting, fewer customer-facing errors and faster onboarding of new systems.
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Frequently Asked Questions
Is the ERP the SSoT for everything?
No. The ERP is the SSoT for what happens inside the ERP's scope — commercial transactions, inventory, fixed assets. For customer relationship data, CRM is typically the SSoT. For product marketing data, PIM. For employee personal data, HCM. The ERP's natural scope is operational and financial; trying to make it the SSoT for everything overloads its functionality and fights what other specialist systems do better.
How does SSoT relate to data warehouses?
Data warehouses consume from SSoTs rather than being them. The warehouse reflects what the source systems hold at any point in time, with snapshots preserving history. If the source SSoTs are inconsistent, the warehouse inherits the inconsistency — data-warehouse work cannot fix upstream governance failures.
Does SSoT prevent the need for master-data management?
No. SSoT is the principle; MDM is the operational discipline implementing it across the application landscape. Without MDM, SSoT is just an aspiration. The two together — SSoT as principle, MDM as practice — deliver the data quality that operational and analytical systems both depend on.