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Ah, the circle of life.

We spend years imagining the day we can move out, chase our dreams, and become successful adults with families of our own.

Usually, our plans don't involve landing back in our childhood bedroom, staring at tattered posters and wondering what we ever saw in Gavin Rossdale. But these days, it's just as common for us millennials to bunk with our parents as it is to buy homes ( especially for women). For some of us, student loans have us playing financial catch-up. For others we just need some temporary digs while we suss out our next job move.

Either way -- when Mom and Dad become your landlord, things get tricky.

Sure, it might be a great way to save some cash and maybe get a few perks out of the deal (parents might be more lax about things like getting a puppy or setting up that sweet retro water bed).

But just because you feel like a kid again doesn't necessarily mean you can act like one. Make sure you know these do's and don'ts before you start unpacking -- or risk some permanent damage to your family dynamic.

Do: Get the lease in writing

OK, it may feel silly and awkward to draw up formal paperwork to stay in the place where your mom used to tuck you in. But if you're renting your folks' guesthouse, attic apartment, or spare room for any amount of time, you should have a written lease.

Not only will a formal agreement come in handy in the event of any disputes with your parents, but it also serves as proof of residency for your rental history, says Jennifer Ruelens, co-founder of Fish Property Management in Williamsport, PA.

Do: Work out the rent in advance

At some point, your parents are going to remind you that you're an adult now, and you have to do adult-y things. Like pay rent.

When the inevitable time comes, you may be able to persuade your parents to give you a sweet break on rent.

Just ask Phillia Kim Downs. The Brooklyn, NY, resident and her husband both lost their jobs in the recession, and rented from her parents for five years while they sought new jobs and saved for a house.

"The total amount my husband and I paid for rent [there] was cheaper than any rent we could have gotten for the prime location we had and the amount of space we had," says Downs, who's now a real estate agent.

Of course, there's also the chance your parents can't afford to give you a break. Or maybe they're just not aware of what's happening in the rental market. But you should be. If you believe your parents are asking too much, don't blame them. But don't hesitate to negotiate, either -- and do it in a professional, prepared way you would with any landlord.

Do: Set boundaries

Whether you're renting the guesthouse or your old bedroom, don't expect your parents to give you the privacy a traditional landlord would. Nosing around is what parents do! But you can gently set some clear boundaries ahead of time.

Let your parents know what your work schedule is like, so they don't wake you up too early. (In fact, you can wake yourself up. You're a grown-up, remember?) And let them know when you have guests, so they won't barge in.

Do: Get your hands dirty

Your mom may be glad to do your laundry, and your dad may take pride in grilling burgers for you and your buddies on the weekend. But that doesn't mean they have to. And they'll likely expect some help in return. Don't scoff if you get asked to help mow the lawn or pick up a new flapper for the toilet.

"The expectations of you as a tenant are higher," Ruelens says. "You should take more responsibility to maintain the property."

All of the light maintenance will probably be on you, but think of all the homeownership practice you'll get!

Don't: Hide the truth

It's tempting to stretch the truth to a landlord when you're having financial problems. But don't beat around the bush with your parents -- you moved in with them because they could help, right?

When Downs and her husband were unemployed, they often struggled to pay her parents the rent on time.

"If it was any other landlord, I would probably have been evicted," Downs says.

Besides, if you aren't upfront, they may pull the parent card and use your situation as a teachable moment. And no one wants to be evicted by their mom.

Don't: Fall into the habit of bickering

They may mean well, but parents can drive us a little batty sometimes. And when you're living under the same roof, sometimes might turn into all of the time.

But when you inevitably get annoyed, don't take the bait. Living in close quarters again can be straining on your relationship, and that strain could last for years after you move out. Take the diplomatic approach when you can.

After all, it might be worth it.