If you have children already, the first thing that goes away when you decide to stay at home is the cost of daycare. However, if you work at home, part of that cost may remain, unless your work is such that you can keep the children home with you. Take a look at how much of your income right now is going to daycare. That cost alone may prove to you that you don't need a high-paying work at home job to stay home – a simpler one may suffice.

There are several other costs that will drop if you stay at home. You'll be in a different tax bracket. You'll probably drive less, eat out less often and you won't need clothes for work, which can save both on shopping and on dry cleaning bills.

When you're figuring out how much it costs you to work outside the home, don't assume that becoming a stay at home or work at home parent will cause you to stop eating out. You will have those days where you decide to take the kids out, more likely than not.

One thing many parents forget to think about when they decide to stay at home is to handle retirement planning. Now, if you're just staying home for a year or two, it's probably not a big deal, but if you plan on staying home for many years, this can be a huge impact on you when you do retire. You may not have the finances to fund your retirement account well when your family is living on only one income, but you should try to do at least a little. See my article on retirement planning for stay at home parents for more information.

Use this information to figure out what you will need to earn while staying at home. Some will be fine as a single income family, but others will need the stay at home parent to earn some kind of income. Ideally, this will be a relatively small amount, as the whole point of having a stay at home parent is to have more time with the kids and benefit them, not maintain a freely spending lifestyle. However, if a single income isn't enough, a work at home job or home business will likely become necessary.

Figure out how much income will be necessary and how much risk you are willing to take. Work at home jobs are harder to come by, but home businesses are by their nature more risky, and it may take a few years to earn an adequate income from a business. Plan accordingly, and know that you might not be able to live your preferred lifestyle right away.

Fortunately, by the time you take out the costs of working outside the home, you will likely find you don't need to earn what you used to. Half or even less of your previous income may be quite adequate. It may require sacrifice, but that's what being a parent is about.