One in every three people between the ages of 18 and 34 still live at home with their parents, according to Stats NZ. How do you navigate sharing household costs with adult children who've either returned home or never left?

One in every three people between the ages of 18 and 34 still live at home with their parents, according to Stats NZ.

How do you navigate sharing household costs with adult children who've either returned home or never left?

Financial planner Vinessa Orsbourn gives tips on how adult children living at home can do their bit

Financial precarity is a big driver behind the growing trend of adult children moving back home, Orsbourn tells Nine to Noon. When they do, parents must set clear boundaries.

"You need to understand why they're moving back in the first place and what they're trying to achieve, if they've got a particular goal in mind that they're striving to achieve."

Understanding why they want to move back in the first place - for example, saving for a home deposit - will help determine the level of support you provide.

"It helps to work them through the numbers and understand what the timelines are going to look like so you can negotiate upfront what's expected."

After you agree on how long your adult child's stay will be, next on the agenda should be establishing a fair amount that they will pay towards household costs.

"It's important to establish clear expectations around either board or rent, chores and any financial contributions.

" 'This is how much you're going to pay that's going to contribute towards water and power. You can pay for your own food and do your own cooking'."

Physical crowding can become an issue, Orsbourn says, and you'll also have to figure out how best to share the living space.

"It is a balancing act. And you do have to push back. And they do have to respect the fact that it is your home.

"After all, they are adults moving back in. They've just got to realise that there are those boundaries. And you've just got to set those boundaries and expectations upfront so that everyone's on the right page, on the same page."

Paying board and sharing the cost of a cleaner are two additional ways adult children can contribute financially, Orsbourn says.

"There is a fine line between offering a supportive safety net and creating a comfortable hammock."

Go to this episode on rnz.co.nz for more details