Except where a summary assessment is carried out by the court, costs payable between the parties are not assessed until the conclusion of the proceedings out of which the order for costs arises, unless the court expressly orders an earlier detailed assessment (CPR 47.1). A Costs Judge or District Judge may make an order allowing detailed assessment proceedings to be commenced where there is no realistic prospect of the claim continuing (Part 47 Practice Direction, para 1.4).  The court may order or the parties may agree in writing that, although the proceedings are continuing, they will nevertheless be treated as concluded (Part 47 Practice Direction para 1.2.)

Similarly, where costs are payable by the Legal Aid Agency, detailed assessment should not be sought until the conclusion of the proceedings or until the discharge of the civil legal aid certificate.

Costs payable to a solicitor by his client are assessed if and when an order for detailed assessment is made (see further Section 26).

An appeal against an order for costs or an order for detailed assessment does not by itself operate as a stay of those proceedings unless the court so orders (CPR 47.2). An application for such a stay may be made either to the court whose order is being appealed or to the court which will hear the appeal.

Extract from the Senior Courts Costs Office Guide 2018