Monthly Payment for kids from the government

Asalamo Aliiom, I live in Canada with my wife and my kids. The government here gives monthly payment, called child tax benefit, to low-income families with kids to help them raise their children.  This monthly payment depends on the total income of the family "total income of the man and the woman". The less the total income, the higher amount of money a family gets. The government, usually, sends this money to the wife by a check, or by any other way, but it's always sent to the woman.  My wife says that this money is hers because it comes to her account and she thinks she should keep this money for herself.  She says that this money is hers because she's not working and she takes care of the children and the house and this money is sent to her from the government because of that.  On the other hand, I think that this money is to help us raise our children and it should be added to the house expenses.  Although I'm working, the government still thinks my income is not enough to support my family and that is why they send us the money.  What supports my point of view is, as I mentioned before, the money that the government sends depends on the total income of the man and the woman.  When the total income reaches a certain amount, the government stops paying because it thinks that the income would be enough for the family.  My question is, should my wife keep the money the government sends or should she add it to the house expenses?  Is it haram if I take this money to cover our expenses?