Vivienne, Universal Credit will be bringing in those changes - as I understand it, a couple will need to be earning the equivalent of the minimum wage x 35hrs to be able to claim UC. It still means that, as long as one parent is working full time, the other can choose to stay at home until the children are 18. Meanwhile, a lone parent has to return by age 5.
Just out of interest, I've played around with figures in the "Entitled to" calculator. To make it easy to enter the details, I've made the assumption that s/he lives in the same area as me (NW England). The maximum Housing Allowance would be £109pw, and I think that would probably get you a 2-3 bed terraced house around here. S/he'd received the following benefits:
Income support - £3822pa
Child tax credit - £6108pa
Council tax support - £715pa (council tax payable would be £773)
Housing benefit - £5685pa
Child benefit - £1789pa
Making a total of £1510pm. If s/he was working 40 hours per week on the minimum wage, and had to put the 2 children in full time child care (I've used local figures again for this - £170pw per child), s/he'd have the following income:
Net salary - £12273pa
Child/working tax credit - £18913
Council tax support - £380pa (council tax payable would be £773)
Housing benefit - £4604pa
Child benefit - £1789pa
Taking off the child care costs, s/he'd be left with £1690pm, making her £180pm better off for working full time.
A couple with the same children, with one partner working full time (NMW) and the other not working, would have the following income:
Net salary - £12273pa
Child/working tax credit - £7993pa
Housing benefit - £2466pa
Child benefit - £1789pa
Making £2043pm. They'd have to pay council tax of £1031pa as the lone parent has a 25% discount.
If both were working full time on the NMW, with the children in the same child care as the lone parent, the figures look like this:
Joint net salary - £24546pa
Child/working tax credit - £13378pa
Housing benefit - £1172pa
Child benefit - £1789pa
Leaving them with £1945pm after child care, and actually financially better off if one parent stays at home. So, who's actually being incentivised to stay at home?