Although Rule 83 allows other possibilities, any period fixed by the EPO will usually be specified in full months which will be calculated from the receipt of the communication by the person to whom it is addressed (see Rule 78(2)). Rule 83 gives precise details for the determination of the day of expiry of the period, whilst Rule 85 contains provisions covering certain contingencies, e.g. that the EPO is not open on the day on which a time limit expires, or that there is a general disruption in the postal facilities between the EPO and a Contracting State.

When proceedings have been interrupted because of the death of the applicant or proprietor or for any of the other reasons specified in Rule 90, time limits are subject to the provisions of Rule 90(4). The time limits for the payment of the examination fee and the renewal fees are suspended (see J 07/83, OJ 5/1984, 211).