Is there any eligibility criteria for NII or just minimum investment of Rs 2 lakh is required?

Any individual investors, NRI, company or trusts etc who bid for more than Rs 2 lakhs are known as Non-institutional bidders. Similar to RII category, they need not to register with SEBI. Non-institutional bidders have an allocation of 15% of shares of the total issue size in Book Build IPO's.

Note that NII category is not being eligible for any discount offered in Retail category.

Qualified institutional buyers are under Regulation 2(1)(zd) of the SEBI Regulations. They should be registered with SEBI.