If you receive a lump-sum payment for the universal child care benefit (UCCB), parts of which were for a previous year, you must report the full amount on your tax return.
If the total of the parts that related to previous years is $300 or more, the Canada Revenue Agency (CRA) will calculate the tax payable on those parts as if you received them in those years. But they will not reassess your returns unless the result is better for you. The special calculation is done only you report the income on line 117. It will not apply if you designated the lump-sum payment benefit to a dependant and entered the amount on line 185.
The RC62 slip, the Statement of Universal Child Care Benefit, shows the total benefit paid in the year in box 10 with a breakdown showing the benefit related to each year.