In a joint bank account, both parties enjoy equal ownership of the funds in the account, including the right to withdraw and deposit funds into the account at any time. Most joint accounts are between spouses or other relatives, such as a senior and her adult child. They don't have to be, however. If you know the other person well, and trust him not to run off with your money, then you can open a joint bank account with just about anyone.
TL;DR (Too Long; Didn't Read)
Any two people that agree to open an account together are eligible to open a joint bank account. This is true even if the two individuals are not related.
Your Relationship is Irrelevant
Nothing prohibits someone from opening a joint bank account with a non-relative. You will find that nearly all banks will accept this type of account so long as you both meet the minimum guidelines such as being over the age of 18 and providing identification. You might also need proof of income if, for example, the account you're opening requires you to deposit a certain amount of money each month. In many cases, you could open several different joint accounts with this person so that you could co-mingle funds among the accounts without withdrawing and depositing individually.
Ideal for Certain People Groups
The greatest advantage of a joint account with a non-relative is the ease with which you can share funds for bills or business expenses. Roommates and business associates, who are not related, often open joint bank accounts to more efficiently manage their funds for expenses. A very common example is business checking. With a joint business checking account, two or more people can share access to an account with business resources.
Both Have Account Access
Under the law, a joint bank account gives authorized signers on the account equal and full access to the account. In other words, the other person has access to all the money. There is no safeguard in place to stop him from accessing and liquidating the account. In addition, the 100-percent ownership arrangement means that no matter who deposits the most money into the joint account, all authorized signers are entitled to all funds. So, while a joint banking arrangement does provide benefits, these drawbacks mean that joint accounts aren't always a perfect solution.
Trust is What Matters
Joint bank accounts with non-relatives are all about trust. It's a good idea to make sure that all authorized signers agree to equally monitor the account using electronic banking or monthly statements. In addition, if anyone on the joint account is married to a person who is not authorized on the account, a divorce in that marriage could put the joint account in jeopardy. You'll need an agreement to liquidate the account if one of you ever found yourself in this situation. Trusting your business partners or roommates is essential for this type of joint banking.