In general, any couples and individuals use joint bank accounts as convenient tools for ordinary banking needs, adding to cash savings or earning interest on bank investment products or etc. A joint bank account is a financial account that is owned by two or more people. All account holders' names are listed on a joint bank account, with one person signing an IRS W9 form for tax purposes. The person who signs the W9 tax form when the bank account was opened owes the income tax on the interest in a joint account. This is usually the first person listed on the account.However, the IRS views each individual on a joint account as a co-owner with equal rights of ownership. Regardless of the relationship between the two individuals, each owner bears an equal amount of responsibility in reporting and paying taxes.The IRS regards any interest, or gains earned on cash or other assets held in a joint bank account as taxable income. Legally, each of you is responsible for paying taxes on half of the earned interest or gains. Common sources of taxable interest in a joint account are funds from interest earned on cash, CD,, bonds and money market accounts. Joint account owners receive a form 1099-INT from their bank in early spring outlining earned taxable interest above $10 from the previous calendar year. For unmarried individuals filing separate returns, a joint bank account can unknowingly trigger a number of potential federal tax complications. For example, the federal gift tax allows individuals to exclude the first $14K for 2013, I guess, of total personal gifts from taxation. Any gifts to individuals or charities outside the exclusion limits are considered taxable gifts by the IRS. Under these guidelines, withdrawals made from the joint bank account past the $14K limit would qualify as a taxable gift from the other owner of the account.