Hi Sai,
Nothing will impact, the system will add the KKC value in the tax value? This settings only use for delivery costs. You can also check the configuration of condition in the document attached in the note 2319788. Either you can use the existing tax code by changing the tax description or create a new tax code. At the time of maintain the tax conditions for the tax code maintain the validity from 01.06.2016.
Regards,
Mukthar