" Don't wait until you've signed a lease to talk about where you see the relationship going. Just because something saves money doesn't mean it's practical.
In the event that one of you is a homeowner or your existing leases don't line up, it's important for the current owner to realize they are moving into a shared sphere. Before you live together, splitting financial duties is fairly simple and rarely awkward.
"There needs to be an understanding on the part of the homeowner that if you're agreeing to cohabitate, what's yours is theirs," Alpert says. Someone buys dinner here, the other picks up a bar tab there.
"If there is a discrepancy in earnings, then a similar percentage seems to work well." Whatever you do, be sure both parties agree wholeheartedly before the move, and don't forget to discuss what will happen in the event that one of you is out of work for a while. Maybe you and your best friend still do sleepovers, or your parents pop by every single Sunday. Not only are you more apt to fight over small differences (see #4), but you're definitely going to depend on each other for much more.
This may not fly once you're sharing space, and you are certain to get a lot of mixed reviews on your move. Cohabitating means sharing big responsibilities: financial, emotional, and practical. You can't realistically bring two vacuums, two blenders, two coffee tables, and 10 frying pans into your shared space.
If you're sure it's a permanent union, go through your things together and get rid of extras in a way that makes you both feel satisfied. "There may be certain things he likes doing or she likes doing, so have a conversation about that." If you're both busy and contributing financially, it's fair that you share household responsibilities.