Your adult kids are back. Now what?

(MONEY Magazine) -- The balancing act between teaching your kids independence and keeping them safe isn't easy. Do you let them climb to the top of the jungle gym? Are they old enough to venture into town to see a movie? What's a reasonable curfew for a teenager ... with a car?

According to the parenting gurus whose books line my shelves, that's supposed to be it. Once college commences, your job is pretty much done. But boomerang kids are now so common that social scientists have dubbed the phenomenon "adultolescence," a period following college that can last five or more years.

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More than 65% of graduates are moving back home, compared with 53% just five years ago. And while the difficult stages of childhood may have had lasting emotional impact, this one has financial ramifications galore for you - about $5,000 a year, on average, in assistance - and your kid.

How did adultolescence come about? Blame rising college costs and rampant consumerism. Today the average graduate emerges with nearly $20,000 in student loans and $4,000 in credit-card debt. Meanwhile, she faces a world in which rents have skyrocketed over recent decades but starting salaries, adjusted for inflation, have dropped 17%. She can't cut it, so she falls back on the bank of Mom and Dad for support in the form of either cash or an invitation to move back home.

Your challenge is to help her weather this period and come out the other side standing on her own two financial feet.

There are two types of adultolescence. The first is one that you and your child see coming. You both know that his starting salary as a sous-chef won't cover his expenses, so you decide he'll stay home for a couple of years and stash some cash.

If this happens, it's imperative that you expect a real financial contribution from your kid, even if you don't need the money.

"When you move home as an adult after college, you get a sense that you're regressing, and that can have a negative effect on your self-esteem," explains Elina Furman, author of "Boomerang Nation" and the soon-to-be-released "Kiss and Run," who lived at home until she was 30. "If you're paying rent, your parents won't treat you like a child. You're buying a bit of respect."

So how much rent is the right amount? Enough so they feel it, not so much that they can't save. The National Foundation for Consumer Credit suggests that a maximum of 35% of an adult's income go for housing. Bill your kid for half that and require him to do something smart with the rest.

When housing prices were cheaper, the standard advice was to save enough for a down payment. Today, it's more likely you'll encourage your child to save enough to set himself up with a decent car and apartment rental.

Beyond that, he should put any extra money toward student loans. A recent survey from Nellie Mae showed that grads find their loan payments, which average $220 a month and last a solid decade, more burdensome as they get older, when expenses like houses and kids come along. And a study from Alliance Bernstein found that grads with large student-loan debts put off marriage and kids because they feel so underwater.

The second kind of adultolescence is unplanned. Your son gets a job, an apartment, a car, and then he can't hack it. If you decide to help, do it in a way that will let him maintain his independence - and his apartment.

"This is not only more empowering emotionally but financially as well," says Dr. Charles Sophy, medical director for Los Angeles County's family services department. "It will be harder for that son or daughter to leave the nest the second time, once they've gone back to the safety of your roof. If you bail a child out completely by insisting he move back home, you're only setting him up to not have the tools the next time around."

It's up to you to decide whether your help takes the form of a gift or a loan. Just be specific. If it's the latter, structure the deal like any banker would. Settle on a payment schedule and interest rate, if any. "Clarify your own expectations with your spouse," Sophy adds, noting that Mom and Dad don't always agree.

If your child isn't covered at her job, make sure you don't allow her to remain uninsured. Nearly a third of 18- to 24-year-olds don't have health insurance, according to the Census Bureau, and a quarter of those who are 25 to 34 go without.

Nine states have passed laws that allow you to pay extra to carry your children on your policy until age 30, and more are studying the issue.

If that's not an option or the cost seems prohibitively high, look into a high-deductible health insurance plan. For a 24-year-old, the tab would run less than $100 a month, according to eHealthInsurance.com. Your kid may balk, arguing that since she's healthy, why bother? Be the parent here, and put it in terms she'll get: "Because it's insurance, honey. Duh."

How do you know that your days of bailing out your kids should come to an end?

Ask yourself a few questions, suggests Furman. "Are they working hard? Are they progressing in terms of saving toward their exit goal? If the answers are yes, you're doing the right thing, and full independence will likely come about on its own. But if you see that your kid is coasting and not saving a dime, your contribution might be crippling him. You may want to push him out early."

David Morrison, founder of Twentysomething, a market research firm that studies Gen Y, suggests monitoring your child's consumption habits. "Today's young adults are definitely spending," he says. "And it's one big reason that today's young adults have less net worth than young adults 15 to 20 years ago. I tell parents this: 'If your child is buying a better car than you or taking better trips, it's time for them to move out.'" Amen.

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Editor-at-large Jean Chatzky appears regularly on NBC's Today show. Contact her at money_life@moneymail.com.