Taxpayers generally must self assess income tax by filing tax returns. Advance payments of tax are required in the form of withholding tax or estimated tax payments. Taxes are determined separately by each jurisdiction imposing tax. Due dates and other administrative procedures vary by jurisdiction. April 15 following the tax year is the last day for individuals to file tax returns for federal and many state and local returns. Tax as determined by the taxpayer may be adjusted by the taxing jurisdiction.