I need to calculate what portion of my 2017 refund is due to child care expenses so that I can reimburse my ex-husband. How do I calculate that?

[TurboTaxJennifer]

The impact of the deduction depends on your income level and your province of residence.

For example, if you reside in Ontario and have an income of under $40,000, a $1,000 childcare deduction would be worth $200.50: $1,000 X the federal tax rate of 15% plus $1,000 X the provincial rate of 5.05%.

It might be simpler to do a "practice" return in TurboTax Online (no charge as you won't be filing it). You can run the numbers with and without the deduction to determine the difference.