What is DIR-3 KYC and what if a director misses it?

It is the MCA's check that each director's contact and identity details are current, filed by 30 September in the years it falls due. A director who misses it has their director number deactivated until the form is filed with a late fee. We remind every director before the date.

Source: DIR-3 KYC FAQs, Ministry of Corporate Affairs, Government of India