# Overpayments and Underpayments Changes to an order after payment (such as adding, removing, or substituting items) may cause the total amount due to increase or decrease. This can result in **overpayments** (the customer has paid more than the final total) or **underpayments** (the customer has paid less than the final total). Common scenarios include: * **Removing products** — decreases the total, potentially creating an overpayment * **Adding products** — increases the total, resulting in an underpayment * **Substituting products** — may increase or decrease the total, depending on the price differences * **Applying or removing discounts** — changes the total due --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.bossithq.com/pos/order-modification/changes-to-an-order/overpayments-and-underpayments.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.