According to T 1409/05 date: 2006-03-30 (OJ 2007, 113) a legally effective – in the terminology of the EPC, an accorded – filing date had several different legal effects. Amongst others:

(a) it marked the beginning of the pendency of a European patent application; Art. 80 EPC 1973 in conjunction with Art. 90(1)(a), 90(2) EPC 1973;

(b) it marked the notional date on which the applicant formally claimed to have deposited his invention with the EPO; and

(c) the filing date defined the state of the art and hence the extent of search and examination, for the purposes of Art. 54(2) and (3) EPC 1973.

The legal effects (a) to (c) ensued immediately when the filing date was accorded. Further legal effects of the filing date unfolded upon publication of the patent application:

(d) It marked the date which counted as the filing date so as to affect other applications for the purposes of Art. 54(3) EPC 1973.

The filing date unfolded still further legal effects on grant:

(e) it marked the starting date for the granted protection envisaged by Art. 64(1) EPC 1973, cf Art. 63(1) EPC 1973; and

(f) the filing date marked the legally confirmed date by which the applicant had deposited the invention for which protection was granted, and as such, recognised the claim of (b).

The board went on to point out that the difference between the legally relevant dates (a) to (f) was clearly shown by the fact that logically they did not need to coincide, although this was the core assumption in the patent granting system established by the EPC.

A filing date for a "normal" application was accorded as soon as the requirements of Art. 80 EPC 1973 were met – apart from other formal issues, such as language etc. If an application was deemed to have been accorded a filing date, an application came into existence. In other words, there was a pending application, and the legal effects (a) to (c) above were obtained.

Conversely, a pending application had always to be deemed to have been accorded a filing date. It was true that the EPC used the notion of an application that was not deemed to have been accorded a filing date; cf Art. 90(2) EPC 1973. However, such a purported application would legally never be pending, as there would be no application; cf Art. 90(2) EPC 1973. Such a purported application was neither searched nor examined, and neither filing, search, examination nor annual fees needed to be paid thereafter. A purported application which did not have a filing date simply did not exist as an application sensu stricto for the purposes of the EPC. This showed that a pending application without a filing date would be in a legal limbo. In other words, the notion of according a filing date was synonymous with the legal recognition of the existence of a pending European patent application.

The board in T 382/94 (OJ 1998, 24) found that the accordance of a date of filing could by its very nature relate only to the whole of the application documents filed in accordance with Art. 80 EPC 1973. The EPC 1973 did not contain any provision which prescribed that the filing date could be accorded to only a part of these documents. As a result, according to Art. 123(2) EPC 1973 the limits for changing or correcting the parts of an application affecting the disclosure (ie the description, claims and drawings) were defined by "what a skilled person would derive ... from the whole of these documents as filed" (G 3/89 (OJ 1993, 117)). The content of the European patent application as filed was established with the description, claims and, where appropriate, the drawings (following G 2/95, OJ 1996, 555).