Alert on any variant whose available quantity falls below zero, and treat each occurrence as evidence of a process fault rather than a number to correct. Negative inventory almost always traces back to goods-in counted without a purchase order to check against, a sales channel writing back late, or a manual adjustment made to make a symptom go away.
Why this one is worth an interruption
Negative inventory is one of the few numbers in a store that is unambiguously wrong rather than merely surprising. Something was sold that did not exist, which means either the count was wrong when it was set or a movement was never recorded.
The temptation is to adjust it back to zero and move on. Doing that destroys the only evidence you had about which process is leaking, and guarantees the same correction next month.
The threshold
There is no threshold to tune here. The interesting settings are about what you capture alongside the trigger.
| Condition | Set it to | Why that number |
|---|---|---|
| Trigger | available quantity below 0 | There is no acceptable amount of this |
| Capture | which location | Multi-location stores leak at one site, not everywhere |
| Capture | which sales channel sold it | Channel write-back delay is a common cause |
| Repeat flag | same SKU twice in 30 days | Once is an incident, twice is a process |
Who should receive it
This is an investigation trigger, so it goes to whoever can look at the history rather than to whoever is nearest.
- Whoever owns inventory accuracy, even if that is a part of somebody's week rather than a job.
- Whoever received the last delivery of that SKU, because goods-in is the most common cause.
- Not the sales or marketing side. There is no action for them and the number will alarm them.
What to do when it fires
- Do not adjust the number yet. Write down what it says first.
- Check the last goods-in for that SKU against the purchase order it belonged to.
- Check whether another sales channel wrote back late, which shows as a sale timed after the stock hit zero.
- Correct the count, and record which of the causes it was, so the second occurrence has something to compare against.
When not to set this alert
There is essentially no case for turning this off. If it is firing so often that it is noise, the noise is the finding: your receiving process is not producing reliable numbers and no threshold will fix that.
The one exception is a deliberate oversell arrangement, where you sell ahead of stock on purpose. In that case exclude those specific SKUs rather than muting the alert.
Common questions
What causes negative inventory in Shopify?
Most often stock received without being counted against a purchase order, a sales channel writing back a sale after stock reached zero, or a previous manual adjustment made to clear a symptom without finding the cause.
Should I just correct the number?
Correct it, but record what it was and which cause you found first. Adjusting silently removes the only evidence about which process is leaking, which is why the same correction comes back.
Is negative inventory always a mistake?
Unless you deliberately sell ahead of stock on specific lines, yes. It means a movement was never recorded or a count was wrong when it was set.