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Patent Law 25. March 2026 · 6 min read

Why the national phase of patent applications is so risky

A PCT application is only as strong as its national phase entry—and this is precisely where entirely unique pitfalls lurk in the U.S., China, Japan, and the U.K.

Introduction: Why the National Phase Is So Risky

The international PCT phase standardizes the procedure; however, during the national phase, each office decides on form, deadlines, and substantive requirements according to its own laws. Mistakes during this transition can quickly lead to loss of rights, unnecessary costs, or weakened intellectual property rights.

Typical problem areas include:

incorrect or missed national deadlines
inadequate or erroneous translations
differing requirements for claim formats
divergent rules regarding amendments and the basis of disclosure

USA: Formal Rigidity and Claim Pitfalls

The U.S. is a key market for many PCT applicants—but, at the same time, one of the most formalistic.

Typical pitfalls:

Failure to comply with U.S.-specific claim rules: impermissible multiple dependent claims and “multiple dependent claims” that in turn depend on multiple dependent claims are not permitted in the U.S. and result in high additional fees.
Incorrect claim numbering: new claims must not be inserted in the middle of the existing set of claims but must be numbered sequentially.
Failure to meet or incomplete fulfillment of formal requirements (Declaration/Oath, inventor information, assignments if applicable) delays the proceedings or jeopardizes the validity of rights.

Practical Tip:

Draft the claim set for the US national phase separately (do not transfer claims 1:1) and deliberately adapt the claim set to US practice (e.g., independent “apparatus,” “method,” and, where applicable, “computer-readable medium” claims).

China (CN): Translation as a Minefield

China is clearly translation-driven: without a clean Chinese version, the entire level of intellectual property protection is at risk.

Specific risks:

Strict deadlines: Entry into the national phase must generally occur within 30 months; late entry is only possible for an additional fee, effectively extending the deadline to 32 months.
Translation quality: Any ambiguity or omission in the Chinese translation may be interpreted as a “voluntary amendment” and narrow the scope of disclosure.
No two-stage filing: Application documents in a foreign language (e.g., English) cannot be filed provisionally with the Chinese translation to be submitted later; the Chinese version must be available in a timely and complete manner.

Practical tips:

Use technical translators with patent experience and ensure close communication between the law firm/patent department and the translator.
Provide a glossary of critical terms (parameters, range specifications, functional designations) and cross-check them against the original PCT text on a random basis.

Japan (JP): Strict Identity and Limited Amendments

Japan places particular emphasis on the identity between the PCT application and the national phase.

Key points:

Deadline and language: Entry into the national phase must occur within 30 months; the Japanese translation must be submitted within two months of national entry.
Identity of documents: National filing documents and translations must, as a general rule, be identical to the published PCT application; a “rewrite” for national entry is not permitted.
Handling of PCT Articles 19/34 amendments: these amendments are optional; if used, they must be correctly submitted as a translation or introduced as part of admissible pre-examination or examination amendments.
Basis of Disclosure: Amendments in the Japanese national phase must be fully supported by the original PCT disclosure; content derived solely from the priority application is insufficient.

Practical Tips:

Determine the PCT Articles 19/34 strategy early so that the “target set of claims for Japan” is already established during the international phase.
Before entering the national phase, verify that all embodiments relevant to Japan are disclosed in detail in the PCT description to safeguard against the need for later amendments.

United Kingdom (UK): Keeping an Eye on Deadlines and Procedural Details

The United Kingdom remains attractive to many PCT applicants after Brexit; nevertheless, specific deadlines and procedural requirements apply.

Relevant pitfalls:

Deadline: national phase in the UK within 31 months from the priority date, with limited possibilities for reinstatement (two additional months in case of unintentional failure to meet the deadline).
No power of attorney required upon entry; this is often mistakenly assumed and unnecessarily formalized.
Search request and examination request:
- Search request and fee within two months of national entry or 12 months from priority.
- Examination request and fee within 33 months from priority.
Inventor designation / Assignment Deed: if the applicant is not the inventor, a corresponding declaration/assignment is required within 33 months (or a shorter period in case of early entry).

Practical Tips:

Plan UK entry together with systematic monitoring of deadlines for search and examination to avoid unnecessary “late fees.”
Simultaneously, assess whether the regional EP route might be strategically more sensible than the national UK route (e.g., consolidation of proceedings).

Strategic Conclusion: PCT Planning with Country Profiles

The international phase should not be viewed as an endpoint, but rather as a bridge to highly diverse national procedures. Developing a country-specific strategy for the U.S., China, Japan, and the UK at an early stage reduces costs, avoids loss of rights, and strengthens the substantive enforceability of subsequent patents.