You are not able to add "Tax" field in Sales Quotes Header using Adaptation mode
The document type of sales quote used in the system has C4C pricing. This pricing does not support tax calculation. Therefore, the "Tax" field is always hidden.
If you configure pricing in an external system, then the "Tax" field can be made visible for documents types that are configured to use the external pricing.
Therefore, the Tax field is offered in the adaptation mode.
KBA , LOD-LE-CQP , Customer Quote Processing , Problem