Whiteways was engaged by Impresa under a DOM/1 subcontract as a plastering subcontractor in connection with works at a hotel. A dispute arose which Whiteways referred to adjudication. Due to the wording of the Notice, Impresa disputed the Adjudicator’s jurisdiction. However, the Adjudicator (with whom the Court agreed) decided that the parties had given the Adjudicator the power to determine his own jurisdiction. The Adjudicator decided in Whiteways’ favour. Impressa argued that Whiteways had been overpaid and sought to abate the claimed amounts. However, the Judge rejected the argument that Impresa had effectively set up an abatement. There was no distinction to be made between set-off and abatement for the purposes of the Act and whichever they might be, notice of such deduction had to be given by way of a withholding notice in accordance with s.111. Although an Adjudicator can make abatements in valuing a claim which has been referred to him whether or not the abatement has been raised in a s.111 notice, however, an Adjudicator cannot look at abatements outside the dispute referred unless they have been specifically included in a s.111 notice.