Can I claim retroactive child support going back several years in Ontario?

Yes, retroactive child support is possible in Ontario. Courts have authority to award support going back to a date before the application was filed — sometimes well before, depending on the circumstances. The leading guidance on this issue comes from the Supreme Court of Canada, which identified the key factors courts weigh when deciding how far back to go.

Courts look at why support was not paid or not sought earlier, whether the payor was notified of the obligation, how blameworthy the payor's conduct was, and whether a retroactive award would cause serious hardship. A payor who knew about an obligation and delayed or avoided paying is treated far more harshly than one who genuinely did not know a child existed or that their income had increased.

There is no hard cutoff, but courts often use the date the recipient first raised the issue as the starting point. Unexplained long delays by the recipient can reduce the retroactive period awarded. Retroactive claims are also more likely to succeed for underpaid support (where an existing order was too low given actual income) than for periods where there was no order at all. A lawyer can help you assess the strength of a retroactive claim based on your specific timeline and evidence.