To add tax quotation by default into pricing quotation, follow these steps:
Go to Admin portal, and navigate to the lefthand panel.
Therein, select Preferences and Settings dropdown menu, and then click on Preferences.
Navigate to Pricing Quotation Preferences, and open that dropdown menu.
To enable tax quotation by default, navigate to the row titled Separate Tax Quotation, select the Edit icon against that row, set value to 'True' into the window that opens and select Update to save changes.
Go back to Design portal, create a new design, and generate your pricing. The changes would be applied.