What Is an Assembly BOM?
A BOM is a list of items and resources that make up a finished product. Items are the physical parts — things you pick from stock. Resources capture the labour needed to build them. Together, they give Business Central what it needs to track costs and manage stock. In addition, the BOM links each part to the finished item, so Business Central always knows what is needed.
There are two BOM types in Business Central: Assembly BOMs and Production BOMs. Production BOMs are for making goods in a factory. They support routings, work centres, and outside work. Assembly BOMs, on the other hand, are for kitting and bundling. You gather parts and sell them as one unit. For example, a shop might bundle a table, chairs, and setup into one item to sell. In that case, an Assembly BOM is the right tool. Similarly, any business that packs items before shipping them to customers can benefit from this feature.
Viewing and Managing Assembly BOMs on the Item Card
In the Business Central item list, the Assembly BOM column shows which items have a BOM. Open the item card and go to Related → Assembly → Assembly BOM. From there, you can view and edit the full parts list.
For example, take the Conference Bundle item 1925-W. Its BOM has a table, a black chair, and a setup resource. You can add lines to include more parts. You can also remove lines to trim the recipe. In practice, the BOM editor is a simple list — you can update it at any time.
Business Central also has a Show BOM button on the item card. This shows the full BOM tree. The finished item sits at the top. All parts appear below it. Furthermore, if any part is itself a BOM, you can expand it to see its sub-parts. This view is most useful when you set up a product for the first time. Use it to confirm the full chain before the first sales order goes out.
Assembly Policy — Assemble to Stock or Assemble to Order
Every item with an Assembly BOM needs an Assembly Policy. You set this under the Replenishment tab on the item card. This setting tells Business Central when to build the bundle. It also affects planning, stock, and shipping.
Assemble to Stock treats the bundle like a normal stock item. Business Central adds it to the planning run and applies reorder points. It also expects stock on hand before orders ship. Therefore, use this policy when demand for the bundle is steady and easy to predict. It works best for bundles with parts that are not used in other products.
Assemble to Order works in a different way. In this case, Business Central does not plan the item in advance. Instead, it creates build work only when a customer places an order. This is the better choice when bundle parts are shared across many products. Pre-building stock would then tie up parts you need elsewhere. In addition, Assemble to Order keeps your part stock free for other uses until real demand arrives. In short, choose based on how steady your demand is and how shared the parts are.
Selling Assembly BOMs on Sales Orders
When you add an Assembly BOM item to a sales order, it appears as one line — just like any other item. From there, however, Business Central gives you two ways to handle it.
The first option is Explode BOM. This replaces the bundle line with separate part lines — one for each item and resource. You are then selling each part on its own. For instance, this works well for line-by-line invoicing. It also helps when a customer wants parts sent to different places. However, once you explode a BOM, the lines are managed on their own. There is no longer a BOM link joining them.
The second option is the Quantity to Assemble to Order field on the sales line. Enter the quantity there. Business Central then creates a build order linked to that sales line. You can open it from the three-dot menu on the line. The build order shows the item, quantity, and all part lines. When the team posts the order, Business Central adjusts stock on its own. Parts go out and the finished bundle comes in. The item is then ready to ship from the sales order.
If the item policy is already set to Assemble to Order, Business Central handles this step on its own. It creates the build order as soon as you add the item to a sales order. As a result, you do not need to enter anything by hand.
Phantom BOMs — Assembly BOMs Within Assembly BOMs
A part on an Assembly BOM can itself be an Assembly BOM. This is called a phantom BOM.
For example, take the Conference Package item 1969-W. Its BOM has two items and a resource. However, one of those items — the Conference Bundle — has its own BOM. That inner BOM has a table, chairs, and a setup resource. So when a customer orders the Conference Package, Business Central tracks parts from both levels at once.
Use phantom BOMs when a sub-item is also sold on its own. They are also useful when you want to reuse a set of parts across many top-level products. Instead of copying the same list on every parent BOM, you define it once and link it where needed. Business Central then works out the full part chain at order time.
Business Central supports up to 50 BOM levels. In practice, however, two or three levels is common. The more levels you add, the more you need to track stock at each layer. A gap at level two, for instance, will block shipping at level one. Therefore, keep your BOM structures as simple as your products allow.
The Show BOM button handles multi-level structures well. Use Expand All to see every part at every level in one view. This is helpful during product setup to confirm the full chain is correct. Moreover, it gives the warehouse team a clear picture of what goes into each bundle. As a result, pick errors and returns go down.
Common Questions About Assembly BOMs
Can you mix items and resources in one BOM? Yes. A BOM can hold any mix of items and work resources. There is no limit on lines. You can also change the BOM at any time. Business Central will use the new version on the next order.
Can you use a BOM with locations? Yes. The build order will use the location set on the sales line. However, make sure all parts are in stock at that location before you post.
Can you report on BOM cost? Yes. Business Central can roll up the cost of all parts in a BOM. This helps you check margins before you set a price. In fact, this is one of the main reasons companies use Assembly BOMs — they get full cost data per finished item.
Can you change a BOM after it is in use? Yes. You can edit the BOM at any time. However, the change will only apply to new orders. Open orders will keep the old BOM lines. So check open build orders if you make a big change.
Can you print the BOM as a pick list? Yes. Business Central has a report for this. In practice, many teams use it as a work order for the build area. It is a quick win for any team that still tracks builds on paper.
Wrapping Up
Assembly BOMs are a core part of Business Central. They handle kitting, bundling, and multi-level product structures with ease. The setup is simple: build the BOM, set the policy, and let the system do the work. In practice, most companies are up and running with Assembly BOMs very quickly.
At NAV SEAL, we help companies set up Business Central to match how their work actually runs. That includes Assembly BOMs, stock policy, and the sales order steps that tie it all together. If you have questions about kitting, bundling, or any other part of your Business Central setup, reach out to us at navseal.com. We are always happy to help.
▶ Are you already using Assembly BOMs in Business Central — or is this the first time you are seeing how they work? Let us know in the comments. And if this was useful, share it with a colleague who is still managing bundle builds by hand.
