http://decision.tcc-cci.gc.ca/tcc-cci/decisions/en/item/73272/index.do 
Ochitaw v. The Queen (September 2, 2014 – 2014 TCC 263) is an arcane decision that illustrates the complexity of some aspect of the treatment of child support under the Income Tax Act. The taxpayer’s position was that since there was more than one child involved, shared custory and his payments were determined by means of an offset from his former spouse he should be entitled to a deduction for one child:
[2] The facts can be briefly stated. Mr. Ochitwa and his wife separated in 2003. They had two children, both minors. They entered a shared custody arrangement and also obtained an order from the Alberta Court of Queen’s Bench, pronounced January 11, 2011 that stipulated:
AND WHEREAS the plaintiff’s guideline income for 2010 is estimated to be $80,000 and the defendant’s guideline income for 2010 is estimated to be $120,000…IT IS HEREBY ORDERED;
1. that the defendant shall pay child support to the plaintiff in the amount of $549 per month commencing January 1, 2011 and on the first day of each month thereafter until further Order of the Court or until such time as the child ceases to be a child as defined by the
Divorce Act.
[3] As Mr. Ochitwa explained, and as confirmed in correspondence from his solicitor, the support amount was based on an offset of the two incomes following the Simplified Federal Child Support Tables for the Province of Alberta, based on support for two children (the difference of $40,000 being the amount by which Mr. Ochitwa’s income exceeded that of his former spouse). Mr. Ochitwa suggested that the support amount to be paid would fluctuate depending on incomes, such that if his ex-wife’s exceeded his, it would be her responsibility to make the support payment. As is clear from the wording of the order this could only be upon issuance of a subsequent order.
…
[7] Mr. Ochitwa questioned why in one shared custody arrangement both parents appear able to obtain the paragraph 118(1)(b) of the Act deduction, yet not able to do so in the other shared custody arrangement. The Respondent, in answer to my query in this regard, wrote as follows:
The Minister of National Revenue confirms that in her view both parents are permitted to make a paragraph 118(1)(b) deduction in example 2, while on Julie is permitted to a paragraph 118(1)(b) deduction in example 3.
In example 2, both parents have a legal obligation to pay child support for their two children under the terms of the written agreement. They may therefore come to an agreement that allows each of them to claim the paragraph 118(1)(b) credit for one of their children, as provided for by subsection 118(5.1).
In example 3, only William has a legal obligation to pay child support for his children under the terms of the court order. Subsection 118(5) prevents him from claiming the paragraph 118(1)(b) credit for either child.
While the offset mechanism worked as though both parties were under support obligations the fact was that his former spouse was, under the terms of the court order cited above, not under any such obligation. While the court expressed some frustration at the legislative scheme it found obliged to dismiss the appeal:
[13] It is not difficult to sense Mr. Ochitwa’s frustration with the legislative scheme and perhaps how it might be manipulated. Unfortunately for Mr. Ochitwa he may well have some legitimate questions regarding the legislative policy underlying these provisions, but that is a matter for the legislators. Under the law, as written, to qualify for the Wholly Dependent Amount pursuant to paragraph 118(1)(b) of the Act the following criteria must be met:
1. At any time in the year the child must be wholly dependent on Mr. Ochitwa (clause 118(1)(b)(ii)(B) of the Act).
2. Mr. Ochitwa is not required to pay support in respect of that child.
[14] When either or both of the children stayed with Mr. Ochitwa, I am satisfied they were at that time wholly dependent on him. He meets the first criteria. With respect to the second criteria, the evidence was that Mr. Ochitwa’s support was based on support for both children. As he was required to pay support in respect of both of the children he fails to meet the second condition. He is not saved by the application of subsection 118(5.1) of the Act as the Court order does not impose a legal obligation on his former spouse to make any support payments.