In the recent Gorska v. Gorski (2015 ONSC 7522) decision, the Superior Court of Ontario dealt with the issue of retroactive support. The court cited the Supreme Court of Canada’s decision in D.B.S. v. S.R.G., 2006 SCC 37 (CanLII), [2006] 2 SCR 231 [D.B.S.], which is considered to be the leading authority on the issue of retroactive support. The following factors are taken into account when making a determination on retroactive support applications:
1. Reasonable excuse for why support was not considered earlier;
2. Conduct of the payor parent;
3. Circumstances of the child; and,
4. Hardship occasioned by the retroactive order.
An award for retroactive support considers the date when the recipient gave the payor effective notice of his or her intention to seek support payments.
If a court is not provided with sufficient evidence to complete the analysis of the factors stated above, for instance, a date for effective notice, or circumstances of the children during the period that support was not paid, retroactive support may not be awarded and may be left to be dealt with at trial.
http://www.canlii.org/en/on/onsc/doc/2015/2015onsc7522/2015onsc7522.html