NEW YORK (TheStreet) -- Just when you thought when you were gone, they pull you back in.

Yes, that's paraphrasing a classic line from The Godfather III uttered by Michael Corleone, but it could be used as easily and in similar anguish by parents across the U.S. when they find out their "grown-up" son or daughter is moving back home with them.

Three in 10 U.S. households are experiencing that, according to a 2012 study from Pew Research, The Boomerang Generation. Last year, Trulia released a survey showing 44% of jobless kids 18 to 34 live with their parents, and so do about 25% of kids with jobs.

To be fair, many households like the arrangement -- as long as junior picks up some of the household expenses tab. Pew reports that 48% of boomerang kids (which it defines as ages 25 to 34) help with the rent or the mortgage and 89% help with the household bills to some extent.

To make sure the living arrangement is a healthy one, emotionally and financially, the California Society of CPAs offers a list of "must haves" before parents agree to re-open their doors and restock the fridge for kids staggering back to the nest.

Also see: More Complicated Modern Families Come With Financial Complications Too>>

Here's the deal:

Teach your children well. Obviously, one big reason so many younger Americans head back to the roost is because they don't have a job -- or money. But some come back home because of poor money management skills, the CSCPA says. So get ahead of the problem in the first place by teaching your kids how to handle money, preferably when they are teenagers or even younger.

That means opening a bank and a retirement account, teaching them how to do their own taxes and keep a budget.

Make it your child's idea. It's best to let your children make the big decision to move back home. Look for red flags ahead of time, such as your child's inability to fill their gas tank, or requests for loans on a regular basis. Step in then and offer financial counseling, and even a loan or two. But avoid advising them to move back in -- it's a "free pass" that enables children and allows them to avoid adult responsibilities.

Establish ground rules. This may seem like a no-brainer, and it truly is. But setting ground rules works only if you talk ahead of a kid's return about such things as paying bills, buying groceries and having friends over late at night. If you don't open those communications lines fully and frankly, you're opening the door for your boomerang child to dodge responsibility and take advantage of the situation.

Also see: Older Consumers Understand Credit Scores Better, But Not Too Much Better>>

Set a deadline. Always think "short-term" for boomerang arrangements. Set a deadline for six months or so, at which point your son or daughter should be back on their feet financially and set to move on again. If you don't, you're once again opening the door to a long-term arrangement, which can drain your independence, and keep your child from succeeding as an adult.

Share the savings plan. One ground rule that can be especially helpful is to schedule regular bank savings "check-ups" with your son or daughter to make sure they are holding up their end of the financial bargain. Agree on a set amount saved that would be enough for your child to get his or her own place, and make sure he or she is advancing toward that financial goal.

A boomerang situation needn't be a negative experience. Instead, view it as a teachable moment, as the saying goes, and forge some personal financial concepts that will stay with your children the rest of their lives.

But preferably in their own residence, and the sooner the better.