I am not an economist or mathematician lol so I probably am being simplistic. But if the govt just took this one action it would help out so many people. Notice I have said for working parents only as if it was extended to everyone there would be a problem with numbers.
Yes there would be a cost to the govt, but mothers would be paying tax on earnings which would offset it to some extent. Also households would be better off as more mothers could actually afford to work, so they would spend more and help the general economy.
We already do it for all 3 year olds so the system for administration is already in place. It would make such a difference to thousands of families struggling atm