If you are selling any food and feed supplement, you have to apply for FSSAI registration. It is mandatory. API stands for Active Pharmaceutical Ingredients. At pharmaceutical ingredients FSSAI doesn’t applicable. FSSAI only applicable to food, feed and dietary supplements.
Read complete procedure for registration: How to Start Food and Feed Supplements marketing and manufacturing Company?
TIN has not any correlation to your personal income. Your firm turnover and income comes under sale tax department.
Read more about TIN/CST/VAT here
Hope Above information was useful to you…