There are certain common expenses you will be sharing your room mates. Some of them are the apartment rent, maintenance bills, groceries that you buy for the house, common house hold items purchases and maid/cook’s salary if you keep one.  By following certain simple protocols you can make your life easier managing all these expenses:

1. Apartment Rent: One person has to take up the responsibility of paying the rent on the time. It’s easier to just set up an auto-transfer instruction with the bank settings to transfer the rent at the beginning of the month. The rest of the folks can do the same to transfer their share of rent to the person who paid for the rent. In case, the person who usually pays the rent to the land lord cannot do it for some reasons for a month, she should communicate it to other room mates so someone else can take up the responsibility.  Paying your apartment rent on time is one of the key factors that keep your relationship with your landlord cordial.
2. Household Items: When you move into a new apartment with room mates you will be buying stuffs like couch, television, beds, curtains so on. These items can be considered as one time expenses. Ideally it’s best if you can minimize common items that are purchased. Stuffs like beds or room curtains, you can probably on personal basis, while other items like common furniture in living room can be made a common purchase. When somebody leaves, you can decide mutually on how much depreciation to apply on the common items and then refund the person’s share accordingly. To find out how much is the depreciated price of the items purchased; you can look it up on online/offline classifieds for similar items.
3. Maintenance Bills: It’s really difficult plus it’s unfair for one person to be responsible for taking care of all the bills. In an ideal case, you can just split the responsibility of who is going to pay which bill. But in real life it won’t probably work. Well an ad hoc assignment of who is going to be paying which bill for the month can still work as long one of you takes the lead to ensure that each bill has been taken care of.  The person paying the bill should put in the receipt in common file that you guys maintain. (Yeah do maintain a file of all payments made, may help out in future in case of some misunderstandings in future)
4. Groceries/Maid Salary/Miscellaneous: These are some other expenses you will be sharing. For groceries, make sure that you do split up the bills fairly. You don’t want your vegan room mate to pay for the Chicken Sausages you guys bought.  Also ensure that you keep your personal purchases that you did with the common items separately. Once again, keep receipts of all purchases made for future reference if required.

One thing you must do is keep track of all expenses incurred. When everything is on record, there are fewer chances of conflicts and more time for fun.