Prioritize a robust WMS with real-time inventory visibility, multi-channel order management, scalable pick-and-pack processes, integrated carrier connections, returns and reverse-logistics workflows, value-added services (kitting/labeling), and transparent KPIs (order accuracy, OTIF, dock-to-stock). Ensure the 3PL supports peak scalability and system integration with your OMS/ERP.

Proximity to Belfast port and arterial routes reduces first/last-mile distance, enabling lower carrier rates and shorter transit windows. It increases routing options for cross-dock and multi-leg shipments, improves consolidation opportunities, and lowers fuel and haulage costs—particularly for frequent small-parcel flows and time-sensitive B2B deliveries.

Benchmark storage (per pallet or ft²), pick/pack fees per order line, receiving and put-away charges, IT/WMS access fees, value-added service rates (kitting/assembly), minimum monthly charges, labor surcharges, peak-season uplifts, and transport pass-throughs. Compare projected cost-to-serve across expected order profiles and service levels.

Conduct operational audits, review SLA and KPI performance history, check client references and case studies, validate WMS and EDI/API integrations, confirm insurance and security standards, assess contingency planning for labor and transport disruptions, and verify certifications for handling regulated or temperature-sensitive goods.