The Canada Revenue Agency allows you to deduct legal fees incurred to increase support, to defend against a claim to decrease support, or to collect unpaid support. Fees to establish child support for the first time are also deductible. Fees for the divorce itself are not tax-deductible.
So, keep your detailed invoices and receipts, to establish that the legal fees you paid were to establish, increase (or prevent a decrease of), or collect support. We provide a letter of attestation of the legal fees attributable to these deductible topics each year, at no additional charge.
Read this Federal Income Tax Department Interpretation Bulletin for more explanations: