Hi Jamie, we're aware of an issue entering negative values on invoices in the iOS app for QuickBooks Self-Employed and our engineers are currently tracking this on investigation INV-71217 - QBSE UK IOS APP - Adding additional product and service with negative figure on the invoice but errors to "Invalid Amount". Please reach our chat support team so that we can add you to this and notify once resolved; in the meantime, please access the browser version to enter the invoices :woman_technologist: