IMO Numbers for Companies and Shipowners

IMO Numbers for Companies and Registered Owners

The IMO ship identification number identifies an individual ship. In addition, the International Maritime Organization (IMO) maintains a separate identification scheme for companies and registered shipowners. A company identifier therefore does not refer to another ship entry: it identifies an organization or a registered owner.

Identifying ships and organizations separately

According to the IMO, a ship’s IMO number remains unchanged throughout its entire life, even if its flag changes. By contrast, the company and owner scheme uses an identifier for each respective organization entry. IMO Resolution A.1215(34), adopted on 3 December 2025, brings both systems together as an integrated identification scheme while maintaining their distinct identities.

The identifier for organizations consists of the letters “IMO”, followed by the category “Company” or “Registered Owner” and seven digits, for example, “IMO Company 8712345”. The category is important: it indicates whether the identifier refers to a company or a registered owner. This scheme should not be confused with a ship’s individual IMO number, even though both may appear in connection with the same ship.

What the number tells you

A Company or Registered Owner number identifies the respective entry. By itself, it does not establish that the company operates a particular cruise brand, nor does it indicate what operational role it plays in relation to an individual ship. The owner, operator and organizer of a voyage may be different companies. The IMO explicitly clarifies that the identification scheme does not determine questions of liability, civil law or other commercial relationships.

The identifier is therefore a key for matching records, not a complete company profile. It can help distinguish organizations with identical or similar names, but it does not replace the role designation in the associated records. The overview Shipping Lines and Cruise Companies distinguishes between brands, organizers, shipowners and operators. For a cruise organizer, the focus is on organizing the voyage, not necessarily on owning the ship.

Assigning information correctly

Ship and company identifiers answer different questions. A ship’s IMO number remains unchanged even when its flag changes; for an explanation of its significance and how it differs from other identifiers, the article Ship Registers and Flag States explains the role of the register. A Company or Registered Owner number, by contrast, belongs to the relevant organization entry. Taken together, the designation, number and role provide an unambiguous identification. Ownership, operation and contractual relationships are described in the relevant company, registry or travel documents. Assigned company and owner numbers, along with associated information, are available in the IMO’s Global Integrated Shipping Information System, or GISIS. The identifier is issued free of charge.