CCB is a income-based, untaxed support for families which already offers that additional support to low-income vs. high-income families that is proposed.  At the lower income you get $533/month/child so for two kids that could be $1066/month.  That's already a decent amount of support. 

Your proposal would get more low-income earning women back in the workforce but for the "middle class" women you'd make the cost to re-entry higher. So more female retail workers and less female engineers would result because those women making about $70k can do the math. The drop in CCB and the daycare cost with no tax rebate means her net is about $14k/year (not including increased commuting costs/clothing etc..), But the retail worker will lose almost $2k in CCB but with free daycare can earn $30k so she's $28k ahead. Whose tax dollars do you want (or should we say need) to fund the program? Female engineer or retail worker. Who do we need more of in the work force?