If a patent is to be applied for in a foreign country, it is possible, in most countries, to apply with priority within 12 months from the filing date of the Norwegian application. The foreign application will then be considered in practice to have been filed at the same time as the Norwegian application.

Eighteen months after the patent application was filed in Norway, it will be made available to the public. After that point it will be impossible to apply for a patent in most foreign countries without claiming priority. A condition for applying for a patent in foreign countries between 12 and 18 months is that neither the applicant nor anyone else has made the invention available (known) to the public.

However, if, within 12 months of the filing date in Norway, a so-called PCT (Patent Cooperation Treaty) application is filed, the priority period may be extended to 30 months and even 31 months for some countries and regions.