PrestaShop 1.6.x. Troubleshooter. Don’t see INCLUDING TAX text on the product page

1. In your PrestaShop admin panel go to Customers->Groups section: 
2. Open Group to order to enable INCLUDING TAX text: 
3. Set the Price display method option to Tax included. Save changes: 
4. Go to the Modules and Services->Modules and Services and in the search field find an Advanced EU Compliance module for editing: 
5. Click the Configure button: 
6. Set the Tax “inc./excl.” label option to Yes. Save the changes: 

Hopefully, this tutorial was helpful for you.