The base date is a contractual mechanism for the allocation of risk between the client and contractor in relation to changes in things such as technical standards and statutory regulations affecting the costs of building works. It generally relates to changes that might occur in the period between the contractor pricing the tender and the signing of the contract, which can often be a considerable period.
For example in the Joint Contracts Tribunal (JCT) Design and Build Contract 2005 (now available in a 2011 edition), the base date determines the allocation of risk in relation to changes in statutory regulations (clause 2.26.11) changes to VAT exemptions (clause 4.4) and changes to definitions of dayworks (clause 5.5). The contractor will not be responsible for changes that occur in these items after the base date.
Traditionally the base date was the date of tender, however this can give rise to uncertainty because of the complexity and duration of tendering procedures. The practice is now to insert a date in the contract linked to the date of return of tenders.
In the JCT Design and Build Contract 2005, clause 1.1 provides for the insertion of a base date, and the guideline is to insert a date that is 10 days prior to the date of return of tender. The 2011 edition does not change clause 1.1.
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