A backorder is an accepted order, or part of one, that remains unfulfilled because the item is unavailable for the required fulfillment. It may have an estimated replenishment date, or the date may still be unknown.
A supplier can backorder your purchase, and your business can accept a customer's backorder. A stockout describes unavailable stock; a backorder describes demand retained for later fulfillment. A stockout may instead result in a lost sale, cancellation or substitute.
Backorder versus partial shipment
A partial shipment supplies part of an order. The remaining quantity may be backordered, scheduled for a later delivery, disputed or canceled. Do not infer the status of the balance from the fact that one shipment arrived.
Keep these quantities distinct:
- Originally requested quantity.
- Supplier-accepted quantity and delivery schedule.
- Quantity physically received and accepted.
- Quantity still outstanding, including any disputed or canceled portion.
A changed ETA is a proposal or update to review, not evidence of delivery. The PO status tracking workflow is the relevant software evaluation when those facts are scattered across messages.
Worked example: the same 15-unit gap
In this fictional example, a retailer ordered 60 units and has already received 40. After subsequent sales, 30 usable units remain on hand. The outstanding 20 units are now expected 15 days from now. Assume demand is exactly three units per day, with no other stock, orders or commitments.
The 30 units cover ten days. The modeled shortage before the delayed receipt is therefore five days × three units = 15 units. The earlier 40-unit receipt is already reflected in current on-hand stock; do not add it again.
Compare responses over that same gap:
| Response | Illustrative incremental cost | Conditions to check |
|---|---|---|
| Wait and lose all 15 sales | 15 × $18 contribution = $270 | Assumes customers will not wait or accept another item |
| Replace 15 units through a backup | 15 × $12 baseline cost × 15% premium = $27 | Backup arrives before the shortage; corresponding original quantity can be canceled without cost |
| Replace with an acceptable substitute | 15 × $2 extra unit cost = $30 | Substitute is approved and available in time; original quantity is resolved |
These figures exclude additional freight, handling and cancellation charges. They compare the extra cost of alternatives, not their full invoice totals. If the original order cannot be canceled, include the additional stock, cash and potential waste exposure before choosing a replacement. The $270 is a modeled lost contribution, not automatically lost revenue or a measured customer-retention effect.
The example makes backup supply look attractive under its assumptions. Different availability, fees, margins or customer choices can reverse the decision.
Questions for the supplier
- Which PO lines and quantities are affected?
- Is the new date a dispatch date or expected usable receipt date?
- Is the date confirmed or still an estimate?
- Can part of the quantity arrive earlier, with what additional freight?
- Are substitutions proposed, and who must approve them?
- Can the outstanding balance be reduced or canceled, and on what terms?
Record the response and the buyer's decision. Placing a backup order does not cancel the original commitment. Keep the unresolved balance visible until the supplier and buyer agree what happens next.
Adjust the plan without confusing delay and demand
A supplier delay changes the supply timeline. It does not necessarily mean customer demand increased. Review the open order, available stock, delivery uncertainty and alternatives before changing a demand forecast or replenishment target.
Repeated delays may justify a different lead-time assumption, supplier arrangement or buffer. Safety stock can absorb some uncertainty; whether it is sufficient depends on the distribution and consequences of shortages. There is no universal delay that is “too large for any reasonable buffer.”
Track performance using consistent requested and accepted dates. Otherwise a supplier can appear on time simply because each late promise replaces the previous one in the report.
Keep the next operator informed
A useful backorder record includes the source notice, original and revised dates, outstanding quantity, chosen response and next owner. Each physical delivery needs its own receipt evidence, even if invoices or freight charges are consolidated.
Use the supplier backorder response guide for the operating checklist. In a LineNow tracking demo, bring one delayed line and a proposed replacement; verify that partial receipts and the remaining commitment stay visible together.