According to the Notices of 2007 (boards of appeal) and 2008 (departments of first instance), a change in the date of oral proceedings can only be requested in case of "serious reasons" justifying the fixing of a new date. The notices give examples of serious reasons including "a previously notified summons [...]"; "holidays which have already been firmly booked"; and "serious illness"; however, differences in detail exist between the two Notices, compare point 2.1 of the 2007 Notice and point 2.3 of the 2008 Notice. Grounds mentioned in the two Notices as not acceptable are, for instance: excessive work pressure, or a summons to oral proceedings before the EPO or a national court notified after the summons in the relevant proceedings.

If the party is represented, the serious reasons must relate to the representative, and not the client (see T 1916/09, T 2125/11, T 231/13).