Since the price and tax rate are specified for the bill of materials product, no individual tax rate is calculated for each bill of materials product (for example, weighted by sub-products). The price of sub-products is shown as 0.00 € on documents and is hidden together with the tax rate on the Shopware standard documents if you have set in the plugin configuration that sub-products should be displayed on documents.
Accordingly, a suitable tax rate must be selected for the bill of materials product. In most cases, this is the respective highest tax rate of the sub-products. In certain cases, however, a lower tax rate may also be possible. For more information, please contact your tax advisor.