Knowing when a divisional application (or, more correctly, a new application under section 15(9)) can be filed is a tricky business in the UK. I have written previously here about how applicants and their representatives can sometimes get caught out by assuming that the same rules apply to those at the EPO. Unlike at the EPO, where the general rule is that a divisional can be filed provided there is a current application pending, in the UK the latest date for filing a divisional is 3 months before the end of the compliance period, provided the application is still pending. This additional requirement can cause problems when applications are still being prosecuted close to the end of the compliance period, especially if it's not yet clear what will get allowed.
According to Rule 30, the compliance period is 4 years and 6 months from the filing or priority date, or 12 months from the date of the first substantive examination report if this is later. The end of the period can be extended by 2 months under Rule 108 without providing any reasons, and may be extended further if evidence is provided. This means that, if the end of the compliance period is getting closer than 3 months, a divisional can still be filed if an extension request is filed in time.
Let's say we are exactly one month away from the end of the compliance period, which for the sake of this example is 30 December 2024. Can we still file a divisional application? The current date is 30 November 2024, which is a Saturday. We have unfortunately left this rather late, as we knew a while back that a divisional application would be needed. As a busy patent attorney, however, we are used to dealing with things at the last minute and we are sure that all will be fine because we can just file a request for a 2 month extension at the same time as filing the divisional application and all will be in order.
Unfortunately, things will not be in order. A further quirk of the UK patent system is that dates on which things are deemed to be filed differ depending on what they are and whether the Office is open. For the purposes of most things the Office is closed at the weekend, meaning that anything filed gets a deemed date of the next working day (see here). This applies to everything apart from new applications that do not claim priority, which get the filing date of the day on which they are actually filed, regardless of whether the Office is open.
The upshot of all this is that the divisional application we filed on 30 November (which did not claim priority) gets that date of filing but the extension request we filed at the same time gets a deemed filing date of 2 December. The result is that the divisional was filed out of time because on the date of filing it was within only 1 month of the end of the compliance period. The only way to rescue this would be to get a further discretionary extension to the compliance period to allow another purported divisional application to be filed within time, but we would have to adequately explain what happened and why this would be justified.
This all sounds very implausible and not something that should happen in the real world. Any competent patent attorney with a reliable docketing system will be warned in good time beforehand about the upcoming deadline for filing any divisional and will not resort to the risky business of filing things on a Saturday evening. This is not, however, a theoretical example but actually happened. The full details can be found in a recent decision from the UK IPO in BL O/0308/25. To prevent further embarrassment to the patent attorney involved, I will not go into any more detail. It is, however, highly recommended reading for all UK patent attorneys, and especially for those involved in marking papers for the patent attorney examinations.
