I dont work in the real estate industry so i can not advise you but my opinion would be that a commission would be 'earned' on the close of any sale (be it houses or widgets!). It may be payable on receipt of the payment, however, if the 'boss' decides to waiver or discount payment then he is choosing to take the hit not your brother. I would believe that your brother earned the commission and should be paid. My advice would be to check his contract of employment and terms and employment. If it isnt explicitly stated otherwise he should request payment from his employer. If its not forthcoming contacting the department of trade enterprise and employment may give him some direction. Reviewing the Payment of Wages Act may also be a starting point.