ABSTRACT
The chapter deals with ascertainment of a claim (also called liquidity) as a requirement for set-off. As far as the ascertainment is concerned, legal systems vary in their approaches: (a) ascertainment as a substantive requirement; (b) procedural approach; (c) judicial discretion; and (d) no ascertainment of the claim. Under (a), ascertainment of the claim is one of the substantive requirements for set-off. If the claim has not been ascertained, it cannot be validly set-off (UNIDROIT Principles, French law). Under (b), ascertainment of the claim is not a substantive requirement for set-off, however, it can be taken into consideration in the civil proceedings (German law). Under (c), it is the judge who is to decide whether or not the set-off of the claim is to be admitted, taking into consideration all the circumstances of the case (DCFR, Dutch law). Under (d), ascertainment of the claim is not a requirement for set-off, either substantive or procedural (Swiss law). The chapter aims to evaluate the approaches and highlight their advantages as well as disadvantages. Special attention is paid to the regulation of the issue in the new Czech Civil Code (in force since 1 January 2014).
