How to File Patents in Multiple Countries

Author: Kanika Sharma

Kanika Sharma

Kanika Sharma

6 min. read

Updated October 25, 2023

Your U.S. patent is granted and you are all set to implement your great idea. It might be releasing a new chain of products, enhancing the ongoing service, or maybe developing a new strategy to promote the brand or business.

But, did you know that if you have a patent granted in the U.S., you can’t stop someone from using your patented invention in China or anywhere outside the U.S.?

Do you know why? Patent laws are country specific, which means a U.S. patent won’t protect your invention outside the purview of the U.S. patent laws.

This is a big problem, isn’t it? So, what’s the solution? One solution would be filing the patent in all the different countries wherever you want to protect your invention—a tedious job.

There’s a better approach. You can file a single international application and mention all the countries where you want to get a patent protection. How to go about it? Well, that’s what I’ll be discussing in this article.

The holy grail of priority date

Before we move on, let me just explain the concept of priority date. For example, you have a rough draft of your invention in your head. You are not clear about the full detailed description, but you want to secure it anyway before coming up with the actual document.  

What should you do?

File a provisional application which will only include a brief summary of your invention. You get 12 months to file a full-blown patent application after filing a provisional patent application. Keep in mind that a provisional application in the U.S. doesn’t offer any protection outside of the US.

How does it help?

The day you file this application, you get a magic date called the priority date. If someone files a similar patent or published some kind of journal disclosing the invention, before you file a full-blown patent application, their disclosure won’t act as a prior art.

A prior art is any document that discloses your invention before the filing date of your patent application. If there exists a prior art for your patent application, your patent stands rejected.

Thus, it is advised that you file a provisional patent application as it gives your patent an edge over other similar patents before you file a full-blown patent application.

So as we are done with the concept of priority date, let’s discuss how you can file a patent application in multiple countries by following the Patent Cooperation Treaty (PCT) route.

Who makes filing a patent application in multiple countries possible?

The PCT allows you to patent your invention simultaneously in different countries with a single international patent application.

There are around 150 countries under the PCT umbrella; by filing one international patent application, an inventor can seek protection in 150 countries simultaneously.

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What’s an international patent application?

An international patent application saves you from the pain of filing a patent application over and over again in multiple countries. All the patent offices of countries that are members of PCT consider an international patent application to be the initial patent application that they have to examine.

An international application is a single patent application that can help you get patent protection in multiple countries (without visiting the patent offices) and replaces all the individual regional or national applications.

How to file a patent application under the PCT

An inventor that wants to file a patent application in multiple countries using the PCT route should first file a patent application with their own national patent office. Within 12 months of the filing date, they will need to file an international patent application under the PCT.

You can also file your international patent application directly with the World Intellectual Property Organization (WIPO), without filing with the U.S. patent office. In fact, no matter which way you choose, your international patent application gets published at the WIPO. The condition for filing is that you have to comply with the national security provisions. You can explore more about directly filing with the WIPO here.

We can roughly divide the entire process of filing patents in multiple countries under the PCT into two phases: international and national. In this instance, the national phase refers to the individual nations (other than the U.S. or your own country) where you’d like patent protection.

International phase

1. Filing

As I’ve mentioned earlier, you can file your international patent application directly with the WIPO or you can follow the other route where you first file a patent application with the U.S. patent office and then file an international patent application.

2. International Search Authority

International Search Authority (ISA) then takes the charge to conduct a patent search to find any relevant patent document and research papers that can challenge the novelty of your patent application.

The ISA provides you an international search report (ISR). The international search report helps you evaluate your chances of securing patents in various countries. The ISA is bound to publish an ISR within 18 months of the earliest filing date.

That is to say, if you file a patent application with your national office on 1/1/2018 and with WIPO on 4/1/2018, then ISA is bound to publish ISR by 6/1/2019.

3. Supplementary international search

In case you have doubts regarding the comprehensiveness of search results in the ISR of your international patent application, and you think there may exist a prior art that can jeopardize your invention, you can request that ISA conduct another search.

This time, a different ISA will conduct a patent search for you. Supplementary international search reduces the possibility of finding a prior art at a later stage. You have to pay additional fees to get a supplementary international search conducted which differs as per the ISA. You can check the fee from Table I(c) here.

After completion of the supplementary search, ISA publishes a supplementary search report which is nothing but another ISR.

4. International Preliminary Analysis

Based on ISR’s search results for your international patent application, you may find some document challenging novelty of your patent application. If you wish, you can use that information to make amendments in your international patent application, which can increase its chance of getting granted.

After amending the claims of a patent application, you can request an International Preliminary Analysis for assessing the patentability of your amended patent application. An international preliminary report on patentability (IPRP), like ISR, helps you assess the chances of your patent application to get granted during the national phase.

After publication of ISR, you have to get a Supplementary International Search or International Preliminary Analysis conducted within 12 months. During these same 12 months, you can decide the countries where you would like to get a patent protection for your invention.

National phase: Starting the patent process in other countries

This is the phase of your patent application where you decide on which countries (outside of your home country) where you want to get a patent protection. If you think that your invention may have chances to perform better in German, Canadian, South Korean, Australian and Chinese markets, you would be choosing patent offices of these countries to begin the national phase of your patent application.

After selecting your desired countries, you pay their fees, submit your translated patent application, appoint a local patent agent, and the like. Their patent office then begins conducting a separate patent search on their end to check the novelty of your patent application to decide whether your application is eligible to receive a patent protection or not.


PCT is a cheaper way to protect your patent application in multiple countries. Aside from that, it also gives you a timeline of 30 months from your earliest filing date to decide countries where you think your invention may have a chance to make money.

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Content Author: Kanika Sharma

Kanika Sharma is a patent research analyst at GreyB Services. GreyB is a technology research and consultancy firm that helps Fortune 500 companies and top law firms across the world with its technological insights.