I have a very affordable single income situation with no kids and I can say that as of almost two years ago when I did the math it took 90k to be in the black and Im to afraid to do the math now. I mean we are talking max frugal living. No body should even contemplate having kids unless they pull in twice that just so they can make sure to make repairs as they need and have a little sanity fun money and be able to save some. That is completely before any actual child expenses at all. So yeah if someone can pull in 200k+ the other can stay at home and it will work but satan forbid that person lose their job without some other income to pick up some of the slack. I can see why 400k would be necessary to account for the reality of serial unemployment.