Keep selected parts under your control and assign the rest of the purchasing scope to the assembly supplier. Partial turnkey works only when both teams share a complete materials responsibility list.

Create a supply-owner column

Mark every BOM line as customer-supplied or supplier-sourced. Include the exact part number, quantity per assembly, delivered quantity, packaging and expected arrival date. Identify customer-supplied bare boards separately. A short email listing a few components is easy to lose when a revision changes.

Review the customer kit

Account for setup and attrition material where required; agree the allowance instead of applying an arbitrary percentage. Label packages with BOM line numbers and part identifiers. Disclose opened moisture-sensitive packaging, special storage instructions and traceability requirements. Request a receiving discrepancy report before a promised production slot depends on the kit.

Define the handoff date

Assembly readiness is the later of bare-board readiness and complete material readiness. A missing low-cost connector can delay the same order as a scarce processor. Confirm the owner of each shortage and whether an approved partial build is technically and commercially acceptable. Document surplus return or storage arrangements at order close.