An item's standard cost is the cost you enter in the Item form. Standard costing is useful for identifying cost and margin variations.
An item's standard cost should be assigned to it for an entire financial period. The item's actual cost may vary, but the cost price shouldn't be changed. Keeping the cost consistent prevents general ledger issues, and gives you a way to identify other factors that are affecting your costing, such as purchase price, usage, or loss. When you need to see up to date information about an item's cost, you can always view its weighted average cost.
Note: If the standard cost price is changed, Vista does not automatically generate a general ledger adjustment transaction. This can lead to issues with standard costing.
Your accountant may make a variance transaction in your general ledger system to account for the difference at the end of the financial period.