Every person holding a Director Identification Number (DIN) must complete an annual KYC filing — DIR-3 KYC — by 30 September. It applies to anyone with a DIN, including directors of dormant companies and designated partners of LLPs.
Miss it and the DIN is deactivated, with a ₹5,000 fee to reactivate. A deactivated DIN blocks every filing that needs the director's signature — which tends to be discovered at the least convenient moment, like the middle of a funding round or an ROC deadline.
It takes minutes when done on time. Put it on the same calendar entry as the AGM and forget about it.