Anyone filing a European patent application that claims a German priority must supply the priority document — yet receives no confirmation from the EPO that it has arrived and been accepted. Since the DPMA joined WIPO DAS there has been an elegant way out. But it is neither automatic nor forgiving of mistakes. A critical assessment — with concrete practical guidance.
Among the inconspicuous but dangerous formalities in European patent proceedings is the priority document. Under Rule 53(1) EPC, an applicant claiming priority must file a certified copy of the previous application within 16 months of the earliest priority date claimed. If the document is not filed in time, the right of priority is at risk (Rule 59, Article 90(5) EPC). This sounds like routine — but it is not, once the document disappears into a “black hole” at the EPO.
No receipt, no certainty
The EPO does not positively confirm the substantive receipt of a subsequently filed priority document. Electronic filing does generate an automatic acknowledgement of receipt for the transmission of the files; however, there is no communication confirming that the document has actually been placed in the file and recognised as compliant with Rule 53. The applicant learns of a problem — if at all — only through an invitation under Rule 59 EPC, and that invitation may come late. In the worst case, the deficiency surfaces only during examination or even in opposition, when a cure is long since impossible and the priority — and with it, potentially, the validity of the patent — has been lost.
Progress with a catch: the DPMA joins WIPO DAS
For a long time this risk could not be avoided elegantly for German priorities, because German priority documents could not be exchanged electronically; the certified paper copy was mandatory. That has changed: since 25 November 2024, the DPMA participates in the WIPO Digital Access Service (DAS) as a “depositing Office” for patents and utility models. A German priority document can now be made available electronically in DAS and retrieved by the EPO — free of charge and without paper (whereas the certified paper copy is subject to a fee).
The catch lies in the procedure. The exchange is not automatic but request-based: the applicant must actively request the DPMA to make an electronic priority document available (form A 9164) and receives a confidential access code. That code must then be communicated to the second office — here the EPO — so that the EPO can retrieve the document from DAS. If either step is omitted, the document is not in DAS, and the certified paper copy — with the confirmation gap described above — remains the only option.
Why Germany remains a special case
To make matters worse, the EPO does not retrieve German priority documents of its own motion. For a number of offices the EPO obtains the document ex officio and without any action by the applicant — for European and EPO-filed PCT first filings, and, on the basis of established exchange arrangements, for Chinese, Korean and US first filings (Rule 53(2) EPC; Guidelines A-III, 6.7). Germany is not on this list for automatic retrieval. For German priorities, therefore, the applicant must always supply the DAS access code. As a result, a German priority is treated, in formal terms, more awkwardly at the EPO than a Chinese or US one — a remarkable state of affairs for the home country of many EPO applicants.
The legal consequence — and why you cannot rely on the safety net
If the document is missing, the EPO invites the applicant under Rule 59 EPC to file it within a specified (in practice two-month) period. If the applicant fails to respond, the right of priority is lost (Article 90(5) EPC). That invitation, however, is no reliable lifeline: its timing is not guaranteed, it may issue late, and a subsequent cure is conceivable — if at all — only under the strict conditions of re-establishment of rights (Article 122 EPC). Anyone who makes the securing of priority depend on an official reminder shifts an avoidable risk onto an uncertain automatism.
How to meet the deadline with legal certainty
In practice, the “black hole” can be defused. The following approach is advisable:
- Choose the DAS route deliberately and early: already at the German first filing, request the electronic priority document (DPMA form A 9164), document the access code and provide it to the EPO (e.g. in the Request for Grant, Form 1001). Retrieval by the EPO is then free of charge and on the record.
- With a paper document — early and with proof: if a certified copy is filed after all, do so via electronic filing well before the 16-month deadline expires; keep the automatic acknowledgement of receipt as evidence of transmission.
- In important cases, use belt and braces: provide the DAS access code and additionally file a certified copy — the minor extra effort is out of all proportion to the threatened loss of priority.
- Verify actively instead of trusting: after filing, check in the European Patent Register (file inspection, “All documents”) and in MyEPO whether the priority document is actually in the file or has been retrieved. Do not wait for a confirmation — none will come.
- Monitor the deadline yourself: docket the 16-month deadline under Rule 53(1) EPC independently and work with a buffer; the Rule 59 invitation is no substitute for your own deadline management.
- Add the DAS request to the first-filing checklist: because the DPMA deposit is request-based, “request electronic priority document” belongs firmly in the workflow of every German first filing from which a priority claim may later be built.
Conclusion
The DPMA’s accession to WIPO DAS is genuine progress — but it removes the legal uncertainty only for those who operate the procedure actively and correctly. As long as the EPO does not retrieve German documents automatically and issues no positive proof of receipt for the priority document, securing priority remains the applicant’s own responsibility. The good news: with the DAS access code, deliberate double protection and a checking glance at the Register, the “black hole” can be closed reliably — one simply has to do it consistently.
