Under the Patent Cooperation Treaty (PCT), you can file a single “international” application that’s effective as an initial application with all PCT member states. This allows you to secure a filing date — while deferring the decision about where you want to pursue patent protection.

If you decide to enter the United States based on a PCT application, you’ll choose between the following two options:

  1. File a traditional national stage of the PCT application under 35 U.S.C 371.
  2. File a new U.S. application under 35 U.S.C. 111(a) claiming priority (under 35 U.S.C. 120) to the PCT application. This is known as a bypass continuation.

At Henry Patent Law Firm, our attorneys frequently assist clients with filing both types of applications. So which option is better for your needs?


Both bypass continuations and traditional national stage applications may lead to similar outcomes, but the option you choose will depend on which process better fits your needs. 

The table below outlines the basic procedural differences between the two:

 Traditional national stage (NS)Bypass continuation (BC)
Filing feesMay be eligible for reduced filing fees (if it was USPTO designated as ISA or IPEA), as provided by 37 CFR 1.492Standard filing fees apply, as provided by 37 CFR 1.16
Priority documentsNo need to resubmit certified copies of foreign priority documents if transmitted to USPTO by International Bureau (IB)Must file certified copies of priority documents (if non-U.S. priority)
Prioritized (“Track One”)/accelerated examinationNot permitted upon initial filing (“Track One” request can be filed later, with RCE)Permitted upon initial filing
New matterNot permittedPermitted in a “continuation in part” (CIP) application. However, new matter is not entitled to earlier priority date of PCT application.
Examination of multiple inventionsUnity of inventionU.S. restriction practice
PCT documentsNo need to refile documents (e.g., international application, article 19/34 amendments) transmitted from IB to USPTOMust file all documents, even those transmitted from IB to USPTO


From the table above, BCs can involve a degree of extra hassle (such as re-filing documents) as compared to NS applications. And for that reason, we generally recommend that our clients file traditional NS applications. Still, we’ve found BCs to be useful under a few circumstances.


If you’ve further developed or modified the inventions described in your PCT application since you originally filed, you can use a BC to capture the material in the PCT application as well as the more recent developments.

You cannot add “new material” to an NS application because it’s treated as the same application as the PCT application. Though you may amend the application at the time of filing or at any time during prosecution, any amendments must still be supported by the original PCT application.

Conversely, BCs are treated as new applications. Generally the rules governing the claims and specification of NS applications also apply to the BC, with one exception: When you file the BC, you CAN add new matter to the specification and claims, so long as the new matter is added at the time of filing.

  • If you file the BC with amendments that add new matter, it’s called a “continuation-in-part.”
  • If you don’t add new matter when you file the BC, it’s called a “continuation.” 

If you file a continuation-in-part, keep in mind that any claims covering new matter will receive a priority date of when the U.S. application was filed — meaning that those claims will NOT enjoy the same priority date as the PCT application.


You can fast track your initial U.S. filing by filing a Track One request for prioritized examination. If you’d like to pursue this option, consider filing a BC.

In a traditional NS application, Track One is available later in the filing process, upon filing a request for continued examination (RCE). 

However, Track One requests require significant additional fees ($2,000 for small entity; $4,000 for large entity). So this option is usually reserved for the highest-priority applications.


Under the PCT, patent applications must meet the requirement for unity of invention, or else the applicant may need to pay additional search fees. 

Here’s how the requirement for unity of invention is defined under patent law: “An international and a national stage application shall relate to one invention only or to a group of inventions so linked as to form a single general inventive concept… Where a group of inventions is claimed in an application, the requirement of unity of invention shall be fulfilled only when there is a technical relationship among those inventions involving one or more of the same or corresponding special technical features.

An NS application would be examined for unity of invention under the same (WIPO) standards as the PCT application.

If the PCT examiner finds a lack of unity in your application, you could get a different result in the United States by filing a BC. This is because a BC would be examined under U.S. restriction rules instead.

According to U.S. restriction rules, “If two or more independent and distinct inventions are claimed in a single application, the examiner in an Office action will require the applicant in the reply to that action to elect an invention to which the claims will be restricted.”

However, U.S. examiners have quite a bit of discretion under U.S. restriction rules, and it’s difficult to predict the outcome for most cases. As such, the differences found in U.S. restriction rules are rarely considered to be a significant factor.


If the circumstances above apply to you, you may want to file a BC — but keep in mind that the following two factors could affect your filing process.


Technically, both BC and NS applications must be filed while the PCT application is pending — in other words, within 30 months of the PCT priority date.

However, if you’re adding “new matter” to a BC, you may want to file the application earlier in order to avoid prior art.

As discussed above, any claims covering the “new matter” will NOT have priority back to to the PCT filing date or the PCT priority date. Consequently, if material from the PCT application becomes publicly available or publicly disclosed in the interim, it can be used as prior art against your claims to new matter.

Common examples of public disclosure include:

  • Publication of the PCT application itself (PCT applications are published after 18 months)
  • Publication by the inventors elsewhere (such as industry journals)
  • Public presentations
  • Public uses or demos of the technology
  • Public sales
  • Corporate publications (such as blog posts or marketing material)

If these disclosures occur more than one year before you file the BC, they can become prior art that can be used against the claims to new matter. But any such disclosures made less than one year before you file the BC will be considered “grace period” inventor disclosures — not prior art.

So if you are adding new matter, you should try to file the BC within a year of any material from the PCT application first becoming publicly available. 


With an NS application, you typically won’t need to file copies of your priority documents, as the International Bureau will send them directly to any designated offices that want to see them.

But with a BC, if there is foreign priority, you’ll most likely need to obtain and resubmit certified copies of the foreign applications — which can increase your filing costs. These copies must be provided within four months from the actual filing date of the application or 16 months from the prior foreign application, whichever is later.


Henry Patent Law Firm’s attorneys and paralegals are experienced with both BC and NS applications, and we can help you determine which approach is best for your IP needs. Contact us now to get started!

Whether you want to know more about the patent process or think we might be a good fit for your needs – we’d love to hear from you!

Michael K. Henry, Ph.D.

Michael K. Henry, Ph.D., is a principal and the firm’s founding member. He specializes in creating comprehensive, growth-oriented IP strategies for early-stage tech companies.