A CIN (Corporate Identification Number) is the unique 21-character alphanumeric code the Registrar of Companies assigns to every company incorporated in India. It appears on the certificate of incorporation and must be printed on letterheads, invoices, notices and other official documents. LLPs get a shorter LLPIN instead.
The 21 characters are not random. They encode the company's listing status (L for listed, U for unlisted), the five-digit industry code, the state of registration (RJ for Rajasthan), the year of incorporation, the ownership type (PTC for private limited, PLC for public, OPC for one person company) and the six-digit ROC registration number. Anyone can decode a CIN, or look it up free on the MCA portal to verify a company exists and check its filing status.
For an MSME owner the practical rule is simple: once incorporated, put the CIN on everything official — letterheads, bills, e-mails used as business correspondence, and your website. Section 12 of the Companies Act 2013 requires it, and the penalty for default is ₹1,000 for every day the default continues, capped at ₹1 lakh (Section 12(8), Companies Act 2013).
Common mistake: confusing CIN with GSTIN or PAN. They are three different registrations from three different departments. Also note the CIN can change — if you shift your registered office to another state or convert from private to public, the ROC issues a fresh CIN, and your stationery needs updating.
More Company & ROC terms
Reviewed to the law in force in FY 2026-27. General information, not advice — confirm the position for your facts before acting.