What is an International (PCT) patent application?

What is an International (PCT) patent application?


PCT is an abbreviation for the Patent Cooperation Treaty, which is administered by WIPO. An international application under the PCT ("a PCT application") is a single patent application which can give rise to rights in over 155 countries which are signatories to the PCT. For these countries, as well as the option of filing a direct national patent application it is possible to obtain protection by filing a PCT application and then later complying with the formalities for the PCT application to be processed in the relevant territory (referred to as "entering the PCT national or regional phase"). The end product is a group of related but distinct national and regional patents.

There are a number of advantages and disadvantages to use of the PCT route which we will discuss below. Please see our separate article for details of the PCT application procedure.


By filing an international (PCT) patent application instead of direct national/regional applications, it is possible to delay the final choice of territories where protection is sought by eighteen months, in respect of territories which are signatories to the PCT. This buys the applicant time to determine which territories will be commercially important.

Filing an international (PCT) patent application also delays the costs associated with seeking protection in each territory which is designated in the international application, both by delaying filing costs until 30 months from the earliest declared priority date and by delaying the subsequent application procedure in some territories.

An international application can be advantageous if you have not yet had any searching carried out. If the International Search Report and Written Opinion are negative and prospects for obtaining patent protection are poor, you need not enter the national or regional phase and therefore never incur the potentially substantial costs to file in multiple territories. In contrast, if you file only direct applications, search reports will not be issued until after the costs of filing the national or regional applications have been incurred.

The PCT includes an optional international examination procedure ("Chapter II"). This procedure is sometimes useful to establish claims which are in principle patentable centrally, and may avoid incurring the costs of making corresponding arguments in multiple territories. It is not always so simple in practice and we have a separate article on whether to file a Chapter 2 Demand.


The most obvious disadvantage of the PCT application route is that it increases overall costs in comparison with filing direct patent applications in the territories where protection is desired.

In some territories, the PCT application route is slower than direct national applications. However, this also means that costs are deferred.

It is also important to appreciate that some commercially-important territories are not signatories to the PCT meaning that direct applications are required instead.

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