How to File a European Patent from the US

If you have a US patent application or a US priority filing, the next step into Europe is usually a European patent application at the European Patent Office (EPO). There are two main ways to get there: file directly at the EPO within twelve months of your first US filing, or enter the European regional phase from a PCT application within 31 months of the earliest priority date. This guide explains the practical path for US companies filing a European patent from the US in 2026.

The direct route is the simplest in theory. You file a European patent application at the EPO and claim priority from your US provisional, non-provisional or PCT application under the Paris Convention. The priority claim must be made at the time of filing, and the EPO may request a certified copy of the priority document. You can file in English, which is one of the EPO official languages, and prosecution proceeds through the EPO's search and examination stages. The direct route is usually best when you already know Europe is the target market and you want to avoid the extra cost of the PCT phase.

The PCT route is more common for US companies with global ambitions. You file a single international application, usually at the USPTO as Receiving Office, and within 31 months of the earliest priority date you enter the European regional phase at the EPO. The PCT gives you a longer decision window, an international search report, and a preliminary non-binding opinion on patentability. It is useful when you are still deciding which markets matter and want to keep options open. The full EPO process is described in the [EPO filing process step-by-step guide](/blog/epo-filing-process-step-by-step).

Both routes converge at the EPO. The EPO examines the application for novelty, inventive step and industrial applicability. Once granted, the patent must be validated in the countries where you want protection, or you can request unitary effect to cover most EU member states with a single right. The choice between validation and unitary effect is covered in the [European Patent vs Unitary Patent comparison](/blog/european-patent-vs-unitary-patent), and the post-grant validation process is explained in the [validating a European patent guide](/blog/validating-a-european-patent).

Before you file, prepare the same core documents as any EPO application: a description, claims, drawings and an abstract. The claims should be drafted with European added-matter rules in mind. Article 123(2) EPC is strict: you cannot add new subject matter after filing. If you claim priority from a US application, the European claims must stay within the scope of the priority document. US-style claim language often needs adjustment for Europe, particularly for software, business methods and medical uses, which face different patentability tests at the EPO.

Representation is a practical requirement. A US patent attorney or patent agent can file a US application and prosecute it before the USPTO, but they cannot represent you directly before the EPO unless they also hold European qualification. Most US companies appoint a European Patent Attorney (EPA) for the EPO phase. A good EPA will review the file before filing, advise on claim strategy, and handle prosecution directly. The [how to choose a European Patent Attorney guide](/blog/how-to-choose-a-european-patent-attorney) covers the questions to ask before you engage.

Deadlines are the main risk. The Paris Convention priority deadline is twelve months from the first filing. The PCT regional phase deadline is 31 months from the earliest priority date. The request for examination at the EPO must be filed within six months of the publication of the European search report. Response deadlines to EPO communications are usually four months. Missing these deadlines is usually recoverable only within limited grace periods and often with extra cost.

Language is rarely a barrier for US applicants. The EPO accepts English as a language of proceedings. You can file the application in English, respond in English, and receive the search and examination reports in English. The only translation costs arise at the post-grant validation stage, where some national offices require translations of claims or the full specification into their national language. For the Unitary Patent, those translation costs disappear in the participating EU states.

Costs are a mix of official fees and attorney fees. EPO official fees for filing, search, designation, examination and grant typically total around €4,000–€6,000. Attorney fees depend on the complexity of the case and the number of examination rounds. A well-drafted application based on a solid US priority usually reduces prosecution cost and improves the granted scope. You should also budget for validation, translation and renewal fees in the countries where you want protection after grant.

A common mistake is waiting until the European phase begins to think about European strategy. The best results come from planning at the US drafting stage: keep the description broad enough to support European claims, avoid subject-matter traps that hurt under EPO practice, and identify your target markets early. Another frequent error is assuming the PCT international search report is the final word on patentability; it is a useful signal, but the EPO will conduct its own search and reach its own conclusions.

The key takeaway is that filing a European patent from the US is a straightforward process when you understand the routes, deadlines and representation requirements. Direct filing is fast and focused. The PCT route gives flexibility. Both require a European Patent Attorney for EPO prosecution and a clear plan for validation or unitary effect after grant. For a broader overview of the service, see [European Patents](/european-patents), and for international European IP services, visit Bauer IP.