The CCTB is a tax-free monthly payment made to eligible families to help with the cost of raising children under 18 years of age. The benefit is based on the number of children in your household and your family’s net income (Line 236 of your T1 General). You should calculate net income by deducting your RRSP contributions, childcare expenses etc. from your total income. It is important to note that the net income threshold below which families are eligible for the CCTB is very high. For example, in 2006 if your family net income is less than $101,000 and you have two children and a stay-at-home spouse, your family will be eligible for the CCTB. You can estimate the CCTB benefits your family could be eligible for using this calculator, but be sure to enter your net income.
The CCTB benefits are not paid automatically even if your family is eligible and both you and your spouse file your tax returns every year. To receive the payments, you should apply to receive the benefit using Form RC66. If you find that you are eligible, do not delay in applying for the benefit because Canada Revenue Agency says that it will only make retroactive payments for up to 11 months from the month in which they receive your application.
For more detail info, please go to Government website: