“Courts ordering a retroactive award must still ensure that the quantum of the award fits the circumstances. Blind adherence to the amounts set out in the applicable guideline tables is not required — nor is it recommended. There are two ways that the federal regime allows courts to affect the quantum of retroactive awards (D.B.S., par. 128). The first involves exercising the discretion that the guidelines allow. Courts may exercise their discretion with respect to quantum in a variety of other circumstances under the guidelines. See: ss. 3(2), 7, 9 and 10 of the guidelines (D.B.S., par. 129). The second is by altering the time period that the retroactive award captures. While the date of effective notice should be chosen as a general rule, this will not always yield a fair result. For instance, where a court finds that there has been an unreasonable delay after effective notice was given, it may be appropriate to exclude this period of unreasonable delay from the calculation of the award. Unless the statutory scheme clearly directs another outcome, a court should not order a retroactive award in an amount that it considers unfair, having regard to all the circumstances of the case (D.B.S., par. 130).
The proper approach can therefore be summarized in the following way: payor parents will have their interest in certainty protected only up to the point when that interest becomes unreasonable. In the majority of circumstances, that interest will be reasonable up to the point when the recipient parent broaches the subject, up to three years in the past. However, in order to avoid having the presumptive date of retroactivity set prior to the date of effective notice, the payor parent must act responsibly: (s)he must disclose the material change in circumstances to the recipient parent. Where the payor parent does not do so, and thus engages in blameworthy behaviour, there is no reason to continue to protect his/her interest in certainty beyond the date when circumstances changed materially. A payor parent should not be permitted to profit from his/her wrongdoing (D.B.S., par. 125).”