Assembly orders in Business Central

Business Central includes an Assembly module — a lightweight production capability available in Essentials (unlike the full manufacturing module, which is Premium). It's designed for kitting, simple assembly, and configure-to-order scenarios where the operation is "combine these components into this finished good" without complex routings, capacity planning, or shop-floor reporting.

Assembly BOMs. An item is marked as assemblable by attaching an assembly BOM — a list of components with quantities and units of measure. Components can be inventory items or resources (time consumed by a person or workstation). Unlike production BOMs (in the Manufacturing module), assembly BOMs are single-level and have no routings.

Two assembly policies.

• Assemble-to-Stock (ATS). The assembly is built into inventory ahead of demand. Common for kits sold frequently, where holding finished kits in stock is faster than assembling on order.
• Assemble-to-Order (ATO). The assembly is built specifically for a customer order. The sales order line carries a quantity, and Business Central automatically creates a linked assembly order that produces the goods when the sales line is released. Cancelling or changing the sales line propagates to the assembly order. This is the powerful pattern — order-driven assembly without manual coordination.

The assembly order. An assembly order has a header (the finished item, quantity, due date, location) and lines (the components being consumed). Status flows: Open → Released → Posted. On posting:

• Components are consumed (item ledger entries posted as outbound, value entries posted at cost).
• The finished item is created (item ledger entry posted as inbound, value entry posted at the cost of consumed components plus resource cost).
• Resource time is captured as resource ledger entries.

Substitutions and variants. Component lines can be substituted at assembly time if the planned component is unavailable. Variants are supported — a kit can be assembled in different colour variants from variant-specific components.

When to use assembly vs production orders.

• Assembly for: kits, simple bundles, configure-to-order with no routing, distribution-style light value-add.
• Production orders for: anything with a routing, capacity planning, subcontracting, finite scheduling, scrap accounting, or shop-floor time reporting.

Assembly is available in Essentials; Production is Premium-only. For customers on Essentials whose needs grow toward routings, this is one of the reasons to upgrade.

Sales integration. ATO assembly orders show on the sales order alongside the line, with full traceability between sales and the build. Posting the sales shipment automatically posts the assembly. Customer documents print only the sales line, not the underlying components, unless explicitly configured.

Reservation. Components on an assembly order can reserve against specific on-hand stock, ensuring the right batch or serial is consumed. Combined with order-to-order binding, this is how MTO businesses keep promises.

Reporting. Assembly orders appear in production-style availability reports and contribute to inventory valuation. Standard reports cover assembly capacity, component consumption, and cost variance.