If the support payments are being made under a court order or a written separation agreement, then I would think the amount he is paying would have been set based upon the allowed tax treatment (deduction to him, income to her). If there is no written agreement or court order, the payments do not have to be treated under the proper tax rules and you would record nothing. If there is a written agreement (but no court order), I suppose that both parties could agree to basically scrap the agreement. If it is under a court order, I don't think you would have any option. If you do end up not taking the allowed deduction, do not record anything on the tax return - if you do, you will have to send in a copy of the written agreement and the CRA will treat it according to the proper rules.