You can set taxes using one of the following three ways:
Utilize the default tax code id in the Sales Invoice and Sales Order field. Due to a limitation with Sage 50 API, sales tax is not automatically calculate. You will need to open invoices/orders with the sale taxes to trigger the calculation. We recommend you use one of the two options:
Separate Tax Lines: Create matching tax lines as line items in the Sage Sales Invoice or Order. The tax line items are assigned to your choosen Sales Tax Payable account (Other Current Liabilities).
Aggregate Tax Lines: Create a single tax line as a line item with the total taxed amount.