There are many different ways to handle finances. I have heard of families that assign certain bills to each person. After they pay the bills, what ever money left over is their own. Other families put all the money together and one person pays all the bills and distribute money to others as necessary.
In a polyamorous family, there are different ways to handle bills. Here's what we do:
Each adult has their own account with a bank card in their name. There is another account that is considered the "Bill Account". Everyone has their paychecks deposited into the Bill Account. All bills are paid from that account according to the budget that is agreed upon by everyone. After all bills are paid (which also includes medical expenses, food, car gas) the remainder is evenly distributed among the family. Some pay periods may see where the adults have to take less money because an emergency came up (illness, child school trip, ect.).
I know our way isn't the only way. I don't claim it is the best way, but it works for us. What ideas or methods do you use?