How long will a boomerang kid stay on your couch?

College grads move back home
College grads move back home

Long before their child earns a college degree, some parents of high school students are already readying their couch in anticipation of a boomerang kid.

About 80 percent of parents expect to support their child financially for at least a few months after graduation, according to a new survey from Upromise by Sallie Mae, which talked to 500 parents with children in high school. That's down from 85 percent who said so in 2014. But more parents seem to be anticipating a longer drain due to tough job markets and student loan debt; 17 percent said they expect their child to need financial support for more than five years after graduation, up from 7 percent last year who were anticipating such a timeline.

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The 500 high school students Upromise surveyed were slightly more optimistic, with 78 percent expecting to receive some financial support after college, and just 10 percent thinking they'll still need that help more than five years post-graduation. "Generally, parents and students expect the student to be coming home," said Erin Condon, vice president for Upromise. But a timeline of five-plus years, she said, "seems excessive."

If that stint entails your grad's living rent-free while you foot all the bills, definitely. But there's some nuance to consider. "We have to interpret, what does help mean?" said certified financial planner Sheryl Garrett, founder of The Garrett Planning Network. Financial support covers a wide range, and could be minimal—parents might be covering specific expenses such as the cell phone bill or auto insurance, for example, or offering a rent-free place to live for a set period of time while their grad saves up for a down payment. "That's quite common for parents to help out in those ways," she said.

Financial support expectations after college

Support timeline Parents Students
No support19.7%21.90%
Up to 6 months17.60%26.90%
6 months to 2 years27.10%24%
2 to 5 years19%17.10%
More than 5 years16.50%10.10%

Source: SOURCE: Upromise.

Garrett recommends thinking in advance about if and how you might like to support your child after graduation. It's as much a financial decision as a personal preference, with adult children tending to boomerang home at a time when their parents should be preparing for retirement. "We have to, as the adult generation, make sure we're taking care of ourselves first," she said. Otherwise, your child might be the one taking care of you, financially, in a few years.

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Don't be reluctant to ask a grad living at home to pay rent or cover other expenses, either, said Condon. A third of parents said their children could stay at home "at no cost," a perk just 22 percent of students expected. Almost half of students said they were willing to pay rent to their parents after graduation, but only 24 percent of parents said they plan to charge it.

If you do decide to offer assistance, set some ground rules in advance so the aid doesn't become enabling. "Make sure it has dollar limits and time limits," said certified financial planner Victoria Fillet, founder of Blueprint Financial Planning in Hoboken, New Jersey. "Otherwise it never ends." She suggests putting a hard stop in place once your graduate secures employment. "Once they get a job, they should live within their means," said Fillet. "That's one of the most valuable lessons that a parent can teach."