My kids father and I live together, however we are not married. Can we file together since we both support the kids

[Marketstar]

No, if you were not married on December 31, 2016, you cannot file a joint return. You will file Single, but  one of you may be able to file as Head of Household (tax wise, more advantageous than Single):

To file as Head of Household, you must:

• Pay for more than half of the household expenses
• Be considered unmarried for the tax year, and
• You must have a qualifying child or dependent

See Guide To Filing Taxes As Head of Household