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Bonx keeps the monetary history of each stock movement. An inbound movement adds value to inventory. An outbound movement removes this value and records it as cost of goods sold, or COGS.
Bonx is the reference subledger for inventory valuation and COGS calculation. It retains an auditable record of every movement and produces the amounts to be posted. Those amounts are then transferred to the company’s accounting software, which maintains the statutory general ledger.

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Keep four amounts separate

Inventory value is not the potential selling price. It is the cost still carried by the available units.

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Calculation principles

Bonx applies these rules to all stock flows:
  • Bonx records each physical movement and its monetary effect in the same operation.
  • Bonx never replaces a validated entry. A correction or reversal creates a new entry linked to the original entry.
  • The cost used for an outbound movement stays attached to that movement. A later price change does not rewrite history.
  • A value of 0 is an explicit cost. A missing value means that the cost is not known. Bonx does not convert missing data to zero.
  • Calculations use quantities with 6 decimal places and unit costs with 4 decimal places. Bonx rounds displayed amounts for the applicable currency.
This journal gives the current inventory value and the value at a past date.

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Select the valuation method

The organization selects one method for interchangeable items. This rule avoids different settings on each article or lot.

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Moving weighted average cost

Each inbound movement recalculates the average cost of the available units:
An outbound movement uses the average cost immediately before the movement.
Example10 units at €10 and then 5 units at €16 give an average cost of €12. An issue of 8 units records COGS of €96. The remaining inventory value is €84.

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First in, first out — FIFO

Each inbound movement creates a cost layer. An outbound movement consumes the oldest layer first.
ExampleAfter the same receipts, an issue of 12 units consumes 10 units at €10 and 2 units at €16. COGS is €132. The remaining inventory value is €48.
Accounting FIFO does not necessarily mean physical FIFOFor fungible or interchangeable items, FIFO determines the order in which inbound costs are assigned to outbound movements. It does not require the warehouse to pick physical units in that order. A company may therefore ship a newer unit for operational reasons while valuing the outbound movement with the oldest inbound cost. Physical traceability continues to show the unit or lot that actually moved; the FIFO layer only identifies the accounting cost consumed.This distinction follows from treating FIFO as a cost-assignment formula for interchangeable items under IAS 2 and, in France, article 213-34 of the French General Chart of Accounts.

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Items managed by unique part or serial number

Unique-part management provides physical traceability. It identifies the unit that was actually received, produced, moved, or shipped. It does not create an individual cost for each serial number. Bonx therefore applies the organization’s weighted average or FIFO method to these items, just as it does to other items. If a production run makes 10 units from shared costs, Bonx allocates the total cost across the 10 units. Each serial number remains physically identifiable, but it does not retain its own purchase or production cost. Bonx does not currently support specific cost identification for genuinely non-interchangeable goods or goods assigned to a specific project. When this method is required, the company reconciles or adjusts the values in its accounting system.

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What Bonx does not treat as a valuation method

An article standard cost provides an estimate when the actual cost is not available. It does not replace weighted average or FIFO. Bonx identifies the estimate and adjusts it when the actual cost becomes available. For now, Bonx does not support the LIFO method. LIFO is not permitted by IAS 2 for IFRS financial statements — including those of listed groups in the European Union — and is not among the methods permitted by the French General Chart of Accounts. It remains permitted under US GAAP in the United States.

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Determine the cost of an inbound movement

The cost depends on the source of the stock. Acquisition cost includes the purchase price after trade discounts. It can also include costs directly attributable to the receipt, such as inbound freight, customs duties, or non-recoverable tax. Recoverable VAT, finance costs, selling costs, and abnormal costs do not increase inventory value. A transfer, split, or merge preserves total value. These operations move or allocate value. They do not create a gain or loss.

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Value a manufactured product

The manufacturing order carries its own cost lines. Each line contains:
  • a name and category;
  • a theoretical quantity;
  • an actual quantity when it is known;
  • a unit, such as h, min, kg, or pce;
  • a unit cost.
Bonx calculates the line amounts as follows:

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Consumed materials

Material lines come from the actual stock issues linked to the manufacturing order. They are read-only. Their cost comes from the valuation journal for the consumed lots, not from the current price on the article record.

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Labour, machine, and other production costs

Users can enter other lines manually or calculate them with a deterministic rule. For example: 2 labour hours at €35 per hour, plus 15 minutes per produced unit. AI can generate the rule from an instruction in the COGS settings. The user checks the result before activation. Bonx then runs the same script with the same data. No AI model takes part in the calculation of a manufacturing order. Categories are classification tags. They do not trigger hidden accounting rules.

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Freeze the production cost

While the manufacturing order is open, Bonx updates its costs from known consumptions and times. At the final stock receipt:
  1. Bonx completes the cost-line calculation.
  2. Bonx uses the actual quantity when available.
  3. Otherwise, Bonx uses the theoretical quantity and identifies an estimate.
  4. Bonx adds the selected amounts.
  5. Bonx divides the total by the good quantity received into stock.
  6. Bonx freezes the lines and records the manufactured product unit cost.
Normal loss therefore increases the unit cost of the good units. Bonx does not automatically allocate a shared cost between multiple products or co-products. Use separate manufacturing orders or provide an explicit allocation approved by finance. A partial receipt uses the costs known at its date. The manufacturing order close posts a new adjustment for any difference. It does not edit validated movements.

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Production example

A manufacturing order produces 10 good units with these costs: The manufactured product enters stock at €73.50 per unit.

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Convert an outbound movement to COGS

Actual COGS arises when a shipment issues stock. It does not arise when the user creates the sales order or invoice. When a shipment is validated, Bonx:
  1. determines the units or cost layers consumed;
  2. records the value removed from inventory;
  3. freezes this value as shipment COGS;
  4. updates the sales-order totals.
Each partial shipment keeps its own cost. A new shipment does not change a previous shipment. Outbound freight, packaging, or preparation costs can appear separately as other variable costs. Bonx does not mix them with inventory cost.

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Returns and reversals

  • A reversed issue creates an inverse entry for the original movement.
  • A linked customer return uses the cost of the original issue.
  • A credit note without a physical return does not change inventory COGS.
  • A late cost correction creates an adjustment. It does not change initial COGS.

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Read COGS and margin on a sales order

The sales order aggregates the costs of its shipments. It keeps actual and estimated values separate.
For a partially shipped order, Bonx shows separately:
  • actual COGS for issued quantities;
  • estimated cost for the remaining quantities;
  • actual margin;
  • projected margin.
This margin is an operational view. It is not an accounting revenue-recognition rule. In the previous example, a shipment of 4 units records COGS of €294. If the corresponding net revenue is €400, the actual gross margin is €106.

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Correct a cost without losing history

Bonx uses three monetary source types:
  • Opening: initializes the quantity and value of existing stock.
  • Movement: values a business inbound or outbound movement.
  • Correction: adjusts a recorded value.
An existing lot must have an opening before its first movement or correction in the new journal. This rule prevents Bonx from building history from a balance with no source. A correction records its cause and effective date. If the affected units remain in stock, it adjusts inventory value. If they were shipped, it adjusts the related COGS.

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Migrate historical stock

Bonx does not replay all historical movements. The migration uses an opening balance at a cutover date:
  1. Select a cutover date.
  2. Correct negative quantities and lots with no usable cost.
  3. Reconcile physical quantities and the existing valuation.
  4. Create one opening entry for each lot in stock.
  5. Confirm that total openings equal the total approved by finance.
  6. Start the new journal from this date.
This method creates a verifiable source without inventing past cost detail.
A valued outbound movement cannot consume more quantity than the journal contains. Correct negative stock and missing openings before you enable the new valuation.

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Precious materials and volatile prices

A change in the market price of gold, silver, or another material does not automatically change inventory value. Bonx keeps the inbound cost and then applies weighted average or FIFO. If net realisable value falls below cost, finance can record an explicit write-down. This entry stays separate from inbound cost and market price. Bonx does not provide automatic fair-value measurement for commodity broker-trading activities. This treatment follows the general principles in IAS 2 Inventories: purchase and conversion cost, specific identification for some non-interchangeable items, weighted average or FIFO for interchangeable items, and comparison with net realisable value. Specific identification remains outside Bonx’s current scope.

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Foreign-currency inventory

Bonx keeps inventory in the organization’s valuation currency. An inbound movement in another currency uses the exchange rate that applies at the movement date. The movement keeps this rate. A later exchange-rate change does not revalue inventory. Bonx records a rate error as a new correction. The accounting system continues to process payment exchange differences. For a sales order in another currency, Bonx converts actual revenue with the rate attached to the shipment. If this rate is missing, Bonx shows COGS but does not calculate margin.

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Prepare a close

Before you use Bonx balances for a close, check:
  • that no stock is negative;
  • that no cost is missing;
  • that physical and valued quantities reconcile;
  • open or partially received manufacturing orders;
  • unprocessed corrections and returns;
  • write-downs approved by finance;
  • consistency between shipment COGS and sales-order totals.
Bonx provides detail from each balance to its movement, shipment, or manufacturing order. The company creates and approves closing accounting entries under its chart of accounts.