In Shopify POS, your staff may have permission to manually edit taxes during a sale. If this happens, the invoice generated may be invalid under Verifactu, SII, or TicketBAI, and could be rejected by the tax authority.
There are two points where this change can occur, and each requires a different solution.
Cart Taxes: Control It with Roles
Shopify POS lets you assign roles to your store staff. Some roles include the ability to edit taxes directly in the cart during the checkout process.
Review your team's roles and disable this permission for cashiers. Tax changes should be reserved for staff with administrative responsibility.
Customer-Level Taxes: Control It with Training
Unlike cart taxes, editing taxes at the customer level cannot be restricted through roles in Shopify POS. There is no setting that prevents it.
This is why it must be covered through mandatory internal training. The instruction for your team must be clear: customer taxes must never be edited or removed under any circumstances. Doing so generates fiscally invalid invoices.