3PL migration guide
A safe 3PL transition starts with a verified operating baseline, not a warehouse move date. Map every SKU, inventory state, integration, open order, return, carrier rule, and customer promise; then test the receiving and order flows before changing routing. Use written entry and exit criteria for each phase so unresolved exceptions do not move silently into launch.
Decision support
Use the same definitions and evidence across every option. A comparison is not reliable when one path uses best-case assumptions and another uses observed operating data.
| Phase | Decision to make | Evidence required | Exit condition |
|---|---|---|---|
| Scope | Which channels, SKUs, inventory states, and order types move? | Catalog export, channel map, open-order report, return queue | Every in-scope flow has an owner and a destination |
| Inventory | How will sellable, damaged, quarantined, and inbound stock transfer? | Location-level count, lot or serial fields, disposition rules | Origin and destination agree on units and status definitions |
| Systems | When do storefront, ERP, marketplace, and carrier connections change? | Field map, test orders, cancellation and refund tests | Each critical transaction passes with traceable IDs |
| Launch | Will routing change at once or by channel/SKU group? | Cutover runbook, rollback trigger, support roster | Go/no-go approval is recorded before traffic moves |
| Reconcile | How will variances and customer-impacting exceptions be closed? | Daily count, order aging, carrier exception, and return reports | Variances are assigned, dated, and closed or accepted |
Execution
Move to the next step only when the evidence and owner for the current step are clear.
Record the current catalog, units by inventory status, open purchase orders, open customer orders, return queue, channel connections, carrier services, packaging rules, and special-handling instructions.
Assign one owner for data, physical inventory, integrations, customer communication, transportation, and finance. Write what the destination must verify before each handoff is accepted.
Use representative orders for standard parcels, multi-line orders, bundles, backorders, cancellations, returns, and any marketplace-specific labeling. Reconcile identifiers across every system.
Use sealed transfer manifests, status-specific counts, inbound appointments, and exception photos. Avoid mixing unverified stock into available-to-promise inventory.
Set a specific switch time, monitor order ingestion and acknowledgements, and retain a documented rollback path until the agreed stability window has passed.
Review inventory variance, order aging, missed service promises, carrier exceptions, support contacts, returns, and invoices on a fixed daily cadence until ownership returns to normal operations.
Boundaries
Primary sources
