generic name of the form used to file taxes payable to a federal, state, or local government. The tax return includes items such as gross income, deductions, tax credits, and tax due. Individual taxpayers file on a calendar year basis using Form 1040m which is due 3 1/2 months after the tax year. Corporations prepare Form 1120 on a calendar year or fiscal year basis. It is due 2 1/2 months after the tax year. The partnership tax return is Form 1065.