IMO Identification Number Schemes

IMO Ship Identification Number Scheme

The IMO ship identification number scheme was introduced in 1987 through adoption of resolution A.600(15), as a measure aimed at enhancing "maritime safety, and pollution prevention and to facilitate the prevention of maritime fraud". It aimed at assigning a permanent number to each ship for identification purposes. The scheme established by resolution A.600(15) was subsequently amended by resolutions A.1078 (28) and A.1117(30), in particular, to extend its scope of application to small ships, including fishing vessels. The IMO number is made up of the three letters "IMO" in front of seven digits (e.g. IMO8712345). Future numbers may be extended to eight digits when the need for more numbers arises. The individual number of a ship remains unchanged during the entire life of the ship, even in case of change of flag, name, ownership or type. The IMO number is inserted in the ship's certificates and is permanently marked on the hull structure of the ship when and where appropriate. As per the provisions of MSC/Circ.1142 - MEPC/Circ.425, all plans, manuals and other documents required by the various IMO conventions to be carried on board ships constructed on or after 1 July 2005 should also be marked with the IMO ship identification number in a clearly legible and unambiguous manner. 

When made mandatory, through SOLAS regulation XI-1/3 (adopted in 1994 and entered into force from 1 January 1996), specific criteria of all passenger ships of 100 gross tonnage and upwards and all cargo ships of 300 gross tonnage and upwards were agreed.

In December 2002, the Diplomatic Conference on Maritime Security adopted a number of measures aimed at enhancing security of ships and port facilities. This included a modification to SOLAS regulation XI-1/3 to require ships' identification numbers to be permanently marked in a visible place either on the ship's hull or superstructure. Passenger ships should carry the marking on a horizontal surface visible from the air. Ships should also be marked with their ID numbers internally.

The IMO ship identification number is assigned to ships, free of charge, by IHS Markit, Maritime and Trade (IHSM) (formerly known as Lloyd's Register-Fairplay) when constructed or later.  The Scheme applies to ships of 100 gross tonnage and above, including fishing vessels of steel and non-steel hull construction; passenger ships of less than 100 gross tonnage, high-speed passenger craft and mobile offshore drilling units engaged on international voyages (SOLAS regulation V/19-1); and to all motorized inboard fishing vessels of less than 100 gross tonnage down to a size limit of 12 metres in length overall (LOA) authorized to operate outside waters under the national jurisdiction of the flag State, with the exception of the following:

  1. ships without mechanical means of propulsion;
  2. pleasure yachts;
  3. ships engaged on special service (For example, lightships, floating radio stations, search and rescue vessels);
  4. hopper barges;
  5. floating docks and structures classified in a similar manner;
  6. ships of war and troop ships; and
  7. wooden ships, other than fishing vessels.

IHS Markit, Maritime and Trade (IHSM) is the sole authority for identifying and assigning an IMO number.  IHSM is able to both validate and issue IMO numbers to Administrations through regular fleet data exchanges with the Administration, as set out in Circular Letter No.1886/Rev.6, as may be amended.

Some public entities are making the use of the IMO Ship Identification Numbers mandatory beyond the sope as required by SOLAS regulation X-1/3 (e.g. some regional fisheries management organizations (RFMOs)).

IMO is cooperating closely with FAO with regard to the development and management of the Global Record of Fishing Vessels, Refrigerated Transport Vessels and Supply Vessels (Global record). The IMO Ship Identification Number is a prerequisite to the first phase of the Global Record.

The management of the IMO Ship Identification Number Scheme also involves the support to the investigation of cases of abandonment of seafarers in order to identify the ships involved, and cases of fraudulent registration.

IMO ship identification number - contact

IHS Markit, Maritime and Trade (IHSM)
(Part of IHS Markit)
Sentinel House
163 Brighton Road
Coulsdon
Surrey CR5 2YH
United Kingdom
Email: ship.imo@ihs.com
International Telephone: (+44)  (0)1334 328300

IMO Unique Company and Registered Owner Identification Number Scheme

The IMO Unique Company and Registered Owner Identification Number Scheme was introduced by adoption of resolution MSC.160(78) in 2004, as a measure to enhance maritime safety, security and environmental protection, and to facilitate the prevention of maritime fraud.  Its purpose is to assign a permanent number for identification purposes to each company and/or registered owner managing ships of 100 gross tonnage and above engaged on international voyages.  Additionally, Administrations are invited to participate in the scheme to the extent they desire by assigning an IMO unique company and registered owner identification number (hereinafter, referred to as "Number") to each company and/or registered owner managing ships of 100 gross tonnage and above not engaged on international voyages.   As per the provisions of resolution MSC.160(78), the IMO unique company and registered owner identification number should be inserted into the following documents: 

  1. Document of Compliance; Safety Management Certificate, Interim Document of Compliance; and, Interim Safety Management Certificate, required by the International Safety Management (ISM) Code;
  2. Continuous Synopsis Record required by SOLAS regulation XI-1/5; and
  3. International Ship Security Certificate and Interim International Ship Security Certificate, required by the International Ship and Port Facility Security (ISPS) Code.

In 2005, by adoption of the proposed new SOLAS regulation XI-1/3-1 on the company and registered owner identification number (resolution MSC.194(80)) (which entered into force on 1 January 2009), the company and registered owner identification number scheme became mandatory to Companies and registered owners of ships to which SOLAS chapter I applies.

The IMO Unique Company and Registered Owner Identification Number Scheme is managed, in parallel with the IMO Ship Identification Number Scheme (resolution A.1117(30)) and as per the procedures for the implementation, as set out in Circular letter No.2554/Rev.3), without charge by IHS Markit, Maritime and Trade (IHSM). The Number consists of seven digits assigned by IHS Markit, Maritime and Trade (IHSM). The label begins with the letters "IMO" followed by either "Company" or "Registered Owner", then, followed by the seven digits.
Once assigned, the Number remains unchanged for a company and/or registered owner. When companies and/or registered owners merge, as a matter of general policy, IHSM assigns the Number of the larger company and/or registered owner to the new amalgamated entity, while the Number of the smaller entity is frozen and not re-used.  

The methods for obtaining Numbers on existing registered owners and companies, for assigning a Number to registered owners or companies that have not previously been assigned a Number and for communicating corrected company details on existing records, on an individual basis, are as follows:

  • a free website which allows registered users to look up Numbers, by using the available "Search" facility.  When the companies or registered owners cannot be identified through the "Search" function, authorized data providers should request the assignment of new Numbers or provide corrective information on existing records.

The website has a free user registration system to enhance both the security of the site and the information:

  • paper request forms; and 
  • a free web service for Administrations to facilitate the provision of individual company and registered owner data from IHSM to flag Administrations in electronic format for ship registration purposes.

IMO unique Company and Registered Owner identification number - contact

IHS Markit, Maritime and Trade (IHSM)
(Part of IHS Markit)
Sentinel House
163 Brighton Road
Coulsdon
Surrey CR5 2YH
United Kingdom
International tel.: (+44) (0)1334 328300
Web:www.imonumbers.ihs.com
E-mail: maritime.owners@ihs.com

The Numbers are also available on the free public website of Equasis (www.equasis.org).