Hello,
Below three is the common cases where the item's cost will get adjusted even after posted sales invoice.
1. The items are still under "Expected Cost" and not "Actual Cost" when you post the sales invoice.
This is where the items are only received but not yet invoiced..
When you post purchase invoice for these items, the system will post adjustment to the item cost and the costing will goes from "Expected Cost" to "Actual Cost".
2. You received the same items on the same date.
For example, the batch of purchase are posted on 1 Jan 2025 at $0.50.
Then you sold the items on 10 Jan 2025.
In any case, if you receive items on 1 Jan 2025 again at $0.45 (backdated posting), the system will post adjustment to the 10 Jan sales invoice.
3. Item Charge
If you post item charge to any posted purchase receipt that was sold, adjustments will be made to cost.