Negative material backflush with non-base UOMs

  • 10 August 2022
  • 5 replies

Userlevel 5

We have recently deployed Acumatica in a live environment, but have noticed some issues on the costing.

It appears that if a Production Order Detail uses material with UOMs other than the base UOM, any negative move would lead to backflushing negative Material Issues of incorrect quantities and amount.


  1. To illustrate this, we tested two production orders - one with materials in the base UOM (KG), one in materials not using the base UOM (MTON). Both are using average valuation / no serial lot tracking, and have negative quantities enabled in Item Class. 
  2. We released a move transaction with 100 qty, then perform a full reversal of the 100 qty by releasing negative move transactions with -1 qty, -50 qty, and -49 qty.
  3. We noticed that the initial incoming 100 qty is treated and converted correctly in both cases.


Material in Base UOM


Base UOM - Material Issues reversed accurately  


  1. However, for non-base UOMs, the reversing Material Issue is incorrect and leaves behind a discrepancy in the WIP balance.


Material in non-base UOM
Base UOM - Material Issues reversed incorrectly, leaving a WIP balance



Anyone here using Production Orders with non-base UOMs noticing a similar WIP errors? Hoping we are misunderstanding some aspect of the system, or if there is a workaround / fix planned for this issue.

Afterall, this does feel like a fairly large oversight, since it completely rules out reversal of production receipts for companies who (a) Use backflushing, and (b) Use non-base UOMs, which should be a non-insignificant portion of Manufacturing users.

WIP variances tend to be substantial as well, per illustrated above - almost none of the original material cost was reversed. 

Things get even stranger in our live version, with the reversing Material issue having more lines than that of the Production Order detail, possibly because we have several of the same materials with differing non-base UOMs on the same Production Order.


Best answer by kokjietan 20 February 2023, 01:49

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5 replies

Userlevel 7
Badge +3

This seems like something which should be routed through Acumatica support.  It is possible this is an issue already identified and resolved.

Userlevel 7

Hi @kokjietan - were you able to find a solution? Thank you!

Userlevel 5

Hi @kokjietan - were you able to find a solution? Thank you!

We were informed by our implementation partner 4 months past that the problem was still in Acumatica’s development backlog.

On our part, I have yet to notice any release notes or known issues posted on this matter. The core problem seems to stem from negative material backflushes taking the wrong unit cost despite different UOMs.

At least for now, I’d recommend others to avoid any negative move/labor if your Production Order has:

  • backflush enabled
  • multiple lines of same UOMS of the same item 


Userlevel 5
Badge +3

Try using Batch Size for items with small UOM’s cut from larger units.  For example, if a 4x8 sheet of something is cut into smaller pieces instead of using a unit conversion of I sheet = 4,608 sq in. and each item is consumes some amount of sq in, instead set the Batch Size to the number of pieces cut from the sheet and the UOM for the sheet as EA.  You will find that the qty and cost calculations to be consistently accurate.  The reason is it cannot calculate the qty and cost accurately for the smaller unit until sufficient production has been reported - which is why the qty seems to be increasing with every move.

Userlevel 1

I also have this issue and all my unit of measure are the same and in the base UOM. I also discovered that if an item has a negative qty in the BOM and considered a By-Product, a negative Move Journal does NOT reverse those as it does for the other (non-by-product) items in the backflushed material journal.


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