If you’re cohabitating (living with someone), you need a cohabitation agreement. That doesn’t mean the world will grind to a halt if you don’t have one, but you’re going into this arrangement without a clear understanding of what happens when conflicts arise. If you want to live with your significant other or even a platonic roommate and have clear expectations, boundaries and consequences, you need to discuss those things in advance and reach an agreement. If not, you may have two completely different sets of expectations going into this arrangement and the law, which provides the default set of rules, may require you or your partner to handle things very differently than what you believe would be fair. I’m not necessarily talking about Sheldon Cooper’s infamous “Roommate Agreement” from The Big Bang Theory, but you can cover a lot of potential pitfalls with a reasonable agreement.

Cohabitation covers a wide range of situations, but the basic scenario is two people who are not married to each other living together. You need to figure out how you’ll handle your finances – from paying monthly bills to putting aside savings. You need to decide how assets will be handled. If you buy things together, who pays for them and how? Who gets to use them? When? How? Who pays for repairs? Are you buying a house together? Does one of you own the house in which you’re both living? Are you both responsible for rent if you’re living in a leased space? Are you included in each other’s estate plans? How about life insurance? What happens if your relationship changes or ends? If you have children together, how will you raise them? I could list a million questions, but I think that provides a taste of what you may need to address.

The purpose of a cohabitation agreement is to eliminate potential conflicts in advance and to provide agreed-upon resolutions of actual conflicts when they arise. You can eliminate potential conflicts by considering ahead of time how you’ll handle finances, parenting arrangements, buying property – pretty much anything you can imagine doing while you’re cohabitating can be addressed in advance. You will have conflicts, disagreements, differences of opinion, or whatever you want to call them. And the more time and effort you put into planning in advance how to resolve those inevitable conflicts, the better position you’ll be in when they actually arise. And if both of you agree, you can change the terms of your cohabitation agreement to meet your changing situation.

Cohabitation agreements can be as creative and inclusive as you both want. You can jointly determine the rules and guidelines and what will happen if you reach a point where you can’t resolve your conflict. It doesn’t matter if anyone else would use the same rules or guidelines because they apply only to you. You can address all of the possible scenarios that come to mind or you can address only the immediate issues that you’re facing when you start to live together. You can also decide in your cohabitation agreement what process you’ll use to end your relationship if you decide it’s not working. You can specify that you’ll use alternative dispute resolution methods, such as the collaborative law process or mediation to reach a resolution, so you can avoid the court system. Without a cohabitation agreement, unmarried couples are caught in a maze of different laws addressing different areas of their relationship.

If you’re living together, you should have a written cohabitation agreement. Set out the rules and expectations in advance so you’re not trying to figure them out as you go along.