The PCT is a multilateral treaty that establishes a procedure for filing a single international application with effect in multiple countries. The PCT provides for the preliminary searching and examination of the application, but it does not eliminate the need to prosecute national patent applications in the individual patent offices where protection is desired. Thus, after the PCT proceedings are concluded, the application still must file separate national applications in each of the designated countries where protection is desired.
The principal advantage of a PCT application is that it extends the deadline for filing national applications in more than 153 countries by at least 8 months, and in most cases by as much as 18 months. Thus if the PCT application is filed within one year of the U.S. filing date, national applications will not be due in the designated countries until at least twenty months from the U.S. filing date, and in most[1] countries not until at least thirty months from the U.S. filing date. This additional time allows the original application to progress further so that the applicant is in a better position to decide whether it is worth proceeding with national applications. This time also allows the applicant to see how the invention fares in the market place, which is also helpful in deciding whether it is worthwhile filing national patent applications.
Another important advantage of the PCT is that it provides for the initial filing of a single application, in English, in the U.S. Patent and Trademark Office. This reduces the up-front costs for international filing, defers the need for multiple copies of the application, drawings, and priority documents, and defers the need for translations. Finally, since a PCT application can be filed in the U.S. Patent and Trademark Office, the applicant can begin an international filing at the last minute, anywhere in the United States, by Express Mailing the application to the U.S. Patent and Trademark Office. The principal disadvantage of a PCT application is that national patent applications still must be filed, and thus the cost of a PCT application is in addition to the cost of regular national filings. U.S. firms are increasingly availing themselves of PCT applications. In 2020 U.S. nationals filed 59,230 PCT applications out of the 275,900 applications filed, or 21%% of the total.
[1] Switzerland*, Denmark*, Finland*, Luxembourg*, Sweden*, Tanzania·, Uganda·, Serbia and Montenegro, Zambia· are the only countries that do not automatically extend the deadline to at least thirty months. However, by going through the EPO filing can be deterred for the countries marked with a *, and by going through ARIPO filing can be deterred for the countries marked with a ·.