Supplementary International Search (SIS)

- the key to a stronger International Patent Application.

The purpose of Supplementary International Search (SIS) is to give PCT applicants the option of requesting supplementary search from one of the participating International Search Authorities (ISA) in addition to the main PCT search, thereby reducing the likelihood of new prior art being found in the national phase.

PCT applicants may request a Supplementary International Search to be carried out by a different International Searching Authority than the Authority handling the PCT application. Nordic Patent Institute is one of the ISAs that offer Supplementary International Searches..

The Search

Nordic Patent Institute offers two types of Supplementary International Searches:

  1. A comprehensive search, which in addition to the PCT minimum documentation, covers the documents in Danish, Icelandic, Norwegian and Swedish held in the search collection of Nordic Patent Institute and its member states. This type of search can be particularly beneficial for applicants when the original ISA was done by another authority, where a “fresh pair of eyes” might be able to spot relevant prior art missed by the ISA.
  2. A “Nordic” search, where only the documents in Danish, Icelandic, Norwegian and Swedish held in the search collection of Nordic Patent Institute and its member states. This is a less expensive option which might be particularly beneficial for applications within certain technologies where the Nordic countries have for decades played a leading role. In particular within the oil and gas technology, marine technology, telecommunication, biotech, chemistry and pharmaceuticals.

The Process

The Supplementary International Search is carried out on the PCT application as filed. The Supplementary Search Authority (SSA) begins the Supplementary Search at the latest by the expiration of 22 months from the priority date.

  • The Supplementary International search report (SSR) shall be established within 28 months from the priority date. The SSR is transmitted to the PCT applicant and the International Bureau.
  • The Supplementary Search is available for any PCT application for which the time limit expires on or after 1 January 2009.
  • The time limit to file the request for the Supplementary International Search is within 19 months from the priority date of the PCT application.

Delivery Time

Nordic Patent Institute delivers the Supplementary Search Report within 2 months from having received the request from WIPO.

The Advantages of Using Nordic Patent Institute for an SIS

  • Nordic Patent Institute draws upon the resources of the national patent offices of the contracting states, thereby strengthening competencies at national level and at the same time exploiting the advantage of having access to the consolidated resources of the national offices.
  • The Institute has a staff of 150 highly qualified examiners, with extensive experience in a broad range of technical areas. This experience is developed through examining a large number of patent applications in areas where NPI’s national industries are strong, for instance oil and gas, biotechnology, pharmaceutical compounds, ships and vessels, chemistry and metallurgy. 
  • Nordic Patent Institute has a quality management system based on ISO standards, and uses only ISO certified contractors. The Danish and the Norwegian national patent offices, who perform the searches on behalf of NPI, are ISO 9001 certified.
  • Nordic Patent Institute has a "European" search procedure based on IPC rather than US classification, and the examiners are skilled in both classification systems.
  • Our examiners have multilingual skills. They master the Nordic languages as well as the most common European languages. This is an advantage when searching in European and Nordic material.
  • We will deliver the Supplementary Search Report within 2 months from having received the request from WIPO. 


The Supplementary International Search request must be filed and fees paid to the International Bureau.

  • For a full supplementary search the fee is the same as for an International Search Report, please consult our fee schedule on the current amount. Click here to see the current schedule fees.
  • For a “Nordic” supplementary search the fee is 4000 DKK


A request for a Supplementary International Search shall be filed at the International Bureau (WIPO). Click here for more information on how to file.

More information

If you would like to know more, you are always welcome to contact us on Tel: + 45 43 50 85 00 or by mail If you prefer to use a more secure way of communication, we offer a Secure File Exchange tool, to communicate and share files with our customers. Learn more about Secure File Exchange and sign up for this service.