Ask a shop floor supervisor how components get consumed on a production order and you will usually get one of two answers. Either someone keys it into a journal, or “the system just does it”. That second answer is flushing, and how you configure it decides how much data entry your team does, how accurate your Work-in-Process (WIP) is at month end, and whether your usage variances mean anything.
It is a small field on the item card and has a surprising amount of downstream effect.
What flushing actually means
In Dynamics 365 Business Central, flushing automatically posts component consumption so no one has to enter it manually in a consumption journal. Materially it moves inventory out of stock and into the production order, which is what creates the value entries behind your WIP.
It only makes sense when usage is predictable. If a product takes exactly four brackets every time, having an operator confirm “yes, four brackets” on every order is create unnecessary friction for the user. If usage varies, or if you need to record which lot was used, flushing works against you.
One licensing note before we go further. Production orders, production BOMs and routings are only available on a Business Central Premium Core License with the Production Management module. The Flushing Method field is still visible on the item card under an Essentials license, though it has no effect. Assembly BOMs, which are available in Essentials, have no flushing concept at all. That trips people up more often than you would expect.
Where you set it
Two places for components, and a third that people forget.
On the Item card and the Stockkeeping Unit card, the field sits on the Replenishment FastTab under Production.
The value from the item or SKU is a default. It copies down to the Prod. Order Component line when you refresh the production order, and you can change it there on a single line before flushing happens. That per line override is the useful lever when one component on one order needs different handling.
The third place is Work Center and Machine Center cards, which have their own Flushing Method field. That one controls capacity, not material. More on it below.
The six methods
For years there was only five methods. Pick + Manual was added in to version 26 (2025 wave 1 release) and it came with a behaviour change worth knowing about, covered at the end of this section.
Manual
Nothing happens automatically. Someone posts consumption in the consumption journal, the production journal, or from a mobile shop floor app. You get full control over quantity, lot or serial number, and posting date.
Use this when actual usage varies from the BOM, when the component is expensive enough to be worth counting, or when it carries item tracking.
Forward
Consumption posts up front, based on the expected quantity on the component line.
By default this fires when the production order status changes to Released. It also fires when you choose Refresh on a released order that was created directly at Released status, which catches people out. On those orders you cannot adjust bin codes on the component lines beforehand, because the lines are created and flushed in the same action. If you need to touch bin codes first, create the order as Planned or Firm Planned and then release it.
If the component line has a Routing Link Code, posting happens per operation instead, when output is posted for the linked operation. The quantity flushed is still the expected quantity on the component line, not something derived from actual output.
Forward suits components that are physically moved to the line as soon as the job starts, and cheap consumables where you would rather see the cost early than chase paperwork.
Backward
Consumption is calculated and posted at the end, based on what you actually produced.
By default this fires when a released production order is set to Finished. With a Routing Link Code on the component line, it fires as each linked operation is finished, and the quantity is proportional to the output posted at that operation. Quantity per, times output, adjusted for scrap percentage and the calculation formula on the BOM line.
This is the one most people mean when they say backflushing. It is a good fit for high volume repetitive work where the BOM is reliable and you want the shop floor reporting output only.
Worth being clear about the flip side: if no output is posted, nothing is consumed. An order sitting at Released with materials physically gone from the racks will show zero consumption until someone reports output.
Pick + Manual, Pick + Forward, Pick + Backward
These three behave like their counterparts above, except the components have to be moved by a warehouse document first, and consumption posts from the To-Production Bin rather than from wherever the stock happened to sit.
They apply at locations using advanced warehouse configuration, or basic warehouse configuration with bins mandatory. The document type differs between the two:
- Advanced warehouse: A warehouse pick moves the components to the To-Production Bin.
- Basic warehouse: Pick + Manual produces an inventory pick, and registering it posts the consumption. Pick + Forward and Pick + Backward produce an inventory movement, and consumption is posted by the flushing logic afterwards.
Important note: A component set to Pick + Forward cannot carry a routing link to an operation that is itself forward flushed. The component would be consumed the moment the operation starts, which leaves no window for the pick to happen.
The 2025 wave 1 change
In Dynamics 365 Business Central version 26 onwards you’ll find Pick + Manual exists because Manual used to force a pick at bin mandatory locations. A feature key now separates the two:
- Manual means “no pick, post it yourself”
- Pick + Manual means “pick it, then post it yourself”.
If you turn the feature on, existing Manual items are converted to Pick + Manual so nothing changes underneath you.
Routing link codes
Everything above changes depending on whether a routing link code is in play, so it is worth pinning down what one is.
A routing link code is a short text value you put on a routing line and on the matching BOM lines. It ties a component to an operation. Without it, Business Central treats the whole order as one event, so forward flushes at Release and backward flushes at Finished. With it, flushing happens operation by operation.
Take a two-operation routing, Cut then Assemble. Sheet metal is linked to Cut, fasteners are linked to Assemble. Post output for Cut and the sheet metal flushes. The fasteners stay in stock until Assemble is reported. Without the links, both would post at the same moment regardless of what the floor was actually doing.
This is the difference between WIP that tracks what’s happening in reality and WIP that is a single lump at either end of the order.
Flushing capacity
Work Center and Machine Center cards have the same field, and it controls automatic posting of time.
Set to Manual, someone posts setup and run time in the output journal. Set to Forward or Backward, Business Central posts the expected capacity for you when output is registered, using the times from the routing line.
If you need one operation to behave differently, the method on the work or machine centre can be overridden on the individual routing line.
Use caution here. Automatic capacity posting means your capacity ledger records the standard time, never the actual. Your routing times become a self fulfilling prophecy and you lose the ability to see whether operations are running long. That is fine if you only use capacity for scheduling, but not if you expect to track labour variances.
Bins: Where the material comes from
The three Bin fields matter, and they live on both the Location card and Work and Machine Center cards.
- Open Shop Floor Bin Code.
Where Manual, Forward and Backward components are consumed from. Think of the bucket of screws that lives at the assembly bench. - To-Production Bin Code.
Where picked components land, and where the pick based methods consume from. - From-Production Bin Code.
Where finished output is placed. At the last routing operation this flows through to the Bin Code on the production order line.
When you refresh a production order, Business Central works out the consumption bin in this order. First it looks at the routing line, which carries the bin codes from the work or machine centre, but only if that centre’s location matches the production order line’s location. If that comes back empty, it falls back to the corresponding field on the Location card. If that is also empty, it uses the item’s default bin at that location.
Locations that do not match is the usual reason a bin code turns up blank when everyone expected it to be filled.
What flushing means for finance
Flushing decides when cost leaves inventory, which means it decides what your WIP looks like on any given day.
Forward flushing moves material cost onto the order at release. If orders sit released for two weeks before anyone touches them, WIP is carrying material that is still physically in the rack. Backward flushing does the reverse. Output can be posted and finished goods received while the order still shows no material consumed, so WIP is understated right up until Finished. For orders that cross a period end, this creates a genuine reporting difference, not a rounding issue.
There is an important standard costing implication here. Backward flushing posts the theoretical quantity: the quantity per item multiplied by the output posted. By construction, expected and actual are the same number, so the order can never generate a material usage variance. If the floor is genuinely using more than the BOM says, that loss does not appear in your variance analysis. It appears months later as a stock count adjustment, disconnected from the product that caused it.
If usage variance is something the business wants to manage, the key components should be set to Manual.
Things to look out for
Item tracking
Automatic flushing cannot assign lot or serial numbers. Components with specific tracking generally need to be Manual, or a pick based method where the pick assigns the tracking. This is the most common reason a well intentioned “set everything to Backward” project falls over.
Negative inventory
Forward flushing posts consumption whether or not the stock exists. Without Prevent Negative Inventory switched on in Inventory Setup, you end up with negative quantities and a stream of cost adjustment noise. With it switched on, your production order fails to release, which at least tells someone the truth.
Finished orders do not reopen
There is no going back. Correcting a wrong flush means negative lines in the consumption journal, with matching item tracking if applicable. Test the settings on a handful of items before rolling them across the item master.
Subcontracting
Posting the subcontract purchase order receipt registers output at that operation, which triggers flushing for any components linked to it. Worth walking through before go live, because the trigger sits outside manufacturing and surprises people.
Component substitutions
Swapping a component mid order does not update flushing behaviour for you. The replacement line uses its own item’s method.
How to choose
| Situation | Method |
| Lot or serial tracked component | Manual, or Pick + Manual |
| High value component, usage worth measuring | Manual |
| Usage varies from the BOM | Manual |
| Cheap consumable, stored at the line | Forward or Backward |
| Reliable BOM, high volume, floor reports output only | Backward with routing links |
| Material staged to the line at job start | Forward |
| Bin mandatory or advanced warehouse location | The matching Pick + variant |
| You need real labour times | Manual on the work or machine centre |
The default worth starting from is Manual for anything tracked or expensive, Backward with routing links for everything else, and only reach for Forward when the material genuinely leaves the store at the start of the job.
Final takeaway
Flushing is not really a technical setting. It is a decision about how much you trust your BOM, and about which numbers the business intends to actually manage. Set it item by item with that question in mind, rather than mass updating the whole item master to whichever option sounded most automated.
Behaviour described in this article reflects Business Central version 26 onwards.
Need a hand with manufacturing setup in Business Central?
Flushing problems rarely announce themselves as flushing problems. They turn up as negative stock, WIP that will not tie out at month end, or usage variances nobody can explain. The real cause is usually somewhere adjacent, in routing links, bin setup, item tracking, or how the production BOM was built in the first place.
If your team is spending time reconciling production costs every month, we are happy to take a look.
Get in touch with the EBS team to talk it through.
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Sam Rathnayake is a Microsoft Certified Dynamics 365 Business Central Functional Consultant with over 15 years of experience delivering Microsoft Dynamics NAV and Business Central solutions across Europe, the Middle East, Asia, and Australia. He has led ERP transformations, integrations, and automation initiatives for global organisations. Sam specialises in Business Central architecture, cloud solutions, and helping businesses improve efficiency through technology.