Why split deliveries and backorders need explicit rules
In many Swiss SMEs — trade, light manufacturing, B2B distribution — an order almost never matches a single shipment. Customers accept partial deliveries, some lines remain on backorder due to stock shortages or production priorities, and the invoice arrives at different times from the delivery note or pickup. Without a shared method across sales, warehouse and accounting, the numbers drift: monthly revenue does not reflect warehouse outflows, VAT does not tie to the periodic return and margin per order line becomes unreliable.
Swiss contract law (Code of Obligations, CO) distinguishes between performance of the delivery obligation and performance of the payment obligation; in practice, the contract, general terms and order confirmation define whether each shipment constitutes a standalone “mini-delivery” or the entire order remains a single relationship until completion. Accounting (Swiss accounting rules and, where applicable, Swiss GAAP FER) and value added tax (VAT) follow their own logic: what matters is when the supply is actually performed or invoiced, how inventory and receivables are recorded, and how each delivery note is linked to the tax document.
This guide describes an operational model suited to Swiss SMEs in 2026: from backorder in ERP to partial invoice, from VAT to closing the customer receivable, with attention to margins and inventory — without confusing open orders, prepayments and actual deliveries.
Three invoicing models compared
The choice of model must align with the contract and be communicated to the customer; accounting must apply it consistently across all multi-shipment orders:
| Model | When to invoice | Backorder | Accounting risk |
|---|---|---|---|
| A — On delivery (recommended B2B stock) | One invoice (or debit note) per partial delivery, amounts only on shipped lines | Remaining lines stay on the open order; no revenue until they ship | Low: revenue and COGS aligned with warehouse outflows |
| B — Cumulative invoice at order completion | A single document when the order is complete | Early deliveries without invoice: watch transfer of risk and any contractual clauses | Medium: “delivered but not invoiced” stock must be tracked; monthly margin distorted |
| C — Deposit / advance on order | Advance invoice with VAT shown separately (art. 26 VAT Act), then final invoice with offset | Backorder does not justify advances unless explicitly contracted | High if confused with partial delivery: advances are not full revenue |
For most SMEs with their own warehouse, model A reduces friction with VAT and gross margin calculation. Model B is acceptable only if contractually provided for and if internal controls are introduced on delivered-but-not-invoiced balances. Model C is for financing custom or long lead-time orders, not for “invoicing the shortfall” on lines still on backorder.
Contract, order confirmation and backorder
Points to clarify in writing (GTC, sales conditions or order confirmation) before the first partial shipment goes out:
Partial deliveries permitted
State whether the supplier may ship what is available and deliver the rest within a deadline (e.g. 30 days). Without a clause authorising partial or successive deliveries, the buyer may reject partial performance when the full ordered quantity is already due; in case of default they may set a reasonable deadline for the seller (art. 107 CO) and, if appropriate, withdraw from the contract or claim damages.
Specify whether each shipment creates a separate payment obligation or payment follows the entire order: this affects collections and reminders, not just invoicing.
Backorder and promised dates
Distinguish “confirmed delivery date” from “estimated date”. In ERP, backorder status must update allocated quantity and quantity awaiting supply, so the warehouse does not sell the same unit twice.
For products with shelf life or traceability obligations (food sector, devices), document any substitutions or lot splits already at the first partial shipment stage.
Swiss VAT on partial deliveries
VAT applies to supplies made in Switzerland. For supplies of goods, place of supply and liability generally follow delivery or making the goods available; for services, completion of the supply. Taxpayers who account according to agreed consideration (art. 39–40 VAT Act) include partial invoices issued in the reporting period: tax liability generally arises on issuance of each partial invoice, provided they document supplies actually rendered and not quantities still on backorder.
Common errors: invoicing (and paying VAT on) the entire order while part of the goods is still in the warehouse; issuing a pro forma invoice treated as a tax document; applying the standard rate to lines that should be at a reduced rate only because they are grouped in one incorrect document. Each partial invoice must clearly show quantity, unit price, line discounts and reference to the customer order; for follow-on deliveries, the order number and delivery note reference maintain the chain for any credit notes on partial returns.
Advances: an advance invoice triggers VAT on the amount prepaid; on final delivery, the definitive invoice must show the total amount, total VAT and deduction of the advance already invoiced (including VAT). Do not use advances to “bring forward” invoicing on backorder lines without a contractual basis.
Exports and other foreign supplies with different VAT treatment (e.g. exempt, acquisition tax or import tax) require transport documentation for each shipment; a partial delivery abroad may trigger a distinct tax event from the part still in Switzerland. SMEs with a domestic/export mix must map each delivery note to the correct tax treatment.
Inventory, revenue and margins: avoiding double counting
Goal: every warehouse outflow linked to a partial delivery generates cost of goods sold in the right period, and revenue only on the same quantity basis.
| Event | Warehouse | Revenue | Trade receivables |
|---|---|---|---|
| Partial shipment (model A) | Issue at average cost or FIFO; update balance per SKU | Net revenue on invoiced lines | Open receivable for partial invoice amount |
| Line on backorder | No issue; possible reorder in “on order” | No revenue | No additional receivable |
| Delivery completed (2nd shipment) | Issue remainder | Revenue on newly invoiced lines | New receivable or top-up per practice |
| Delivery without invoice (model B) | Actual issue | Often deferred — requires “delivered not invoiced” sub-account | None until invoicing |
Gross margin per order is obtained by summing partial invoices linked to the same order and subtracting the COGS of the corresponding outflows. If sales and warehouse use different units of measure (cases vs pieces), normalise in ERP before issue. At year-end, verify that no orders remain “partially delivered and partially invoiced” without reconciliation: they are a classic source of physical inventory variances.
Inventory write-downs (obsolescence on slow items, balances tied to cancelled backorders) remain independent of invoicing: a customer who cancels the outstanding portion after two partial deliveries may require order adjustment, a credit note only if something was already invoiced in error, and return to stock with any value adjustment.
Trade receivables and collections on multi-shipment orders
Due dates and reminders
With model A, each partial invoice has its own due date (30/60 days net). Total exposure to the customer is the sum of open documents, not the original order amount. Credit limits and insurance cover (credit management) should be calibrated to outstanding balance, including deliveries already made.
Partial payments and allocations
Collecting a lump sum “on the order” without allocation per invoice creates phantom open items. Record each payment against the invoice number; for cash discounts, apply them to the specific document. Returns on a single partial shipment are handled with a partial credit note and goods return to warehouse.
Recommended operational flow in ERP
- Customer order confirmed with “partial deliveries allowed” flag and line dates where possible.
- Stock allocation: available to shipment; remainder on backorder with reason (procurement, production).
- Picking and delivery note only on shipped lines; signature or proof of delivery archived.
- Partial invoice generated from the delivery note (not the whole order); automatic check invoiced quantity ≤ delivered quantity per line.
- Accounting entry: revenue, VAT, receivable; warehouse issue with same document reference.
- When backorder stock arrives: second shipment, second invoice; close order when ordered quantity = delivered = invoiced.
- Monthly: open orders report, backorder aging, “delivered not invoiced”, reconciliation of sales VAT vs delivery notes.
Errors that distort margins and the VAT return
Invoicing the entire order on the first shipment
Inflates period revenue and VAT; warehouse appears understated. Correction: credit notes and re-invoicing partially — costly and visible in audit.
Issuing stock only when the order is closed
Understates COGS and overstates margin until closure; physical inventory does not match the books.
Treating backorder as lost sale without releasing commitments
“Reserved” quantities block purchasing and production; realign customer order and supplier orders.
Confusing advance payment with partial delivery
An advance does not replace delivery documentation; VAT and revenue follow different rules.
How Accountex helps keep operations and books aligned
Accounting software integrated with sales and warehouse reduces manual work on partial deliveries: cross-references between order, delivery note and invoice, VAT entries consistent with the actual method and receivables position per customer always up to date. Dashboards on open orders and revenue still to invoice let the owner and trusted advisor spot variances before monthly close or the quarterly VAT return.
Defining the rules once (invoice on delivery, transit accounts if needed, document numbering) and applying them uniformly beats periodic corrections: it is the basis for reliable margin by product and customer, credible inventory and tax compliance in a Swiss SME context.