Taxpayers will have until Monday, April 18 to file their 2010 tax returns and pay any tax due because Emancipation Day is a holiday observed in the District of Columbia. It is on April 15th, so by law, DC’s holidays impact tax deadlines in the same way that federal holidays do; everyone (persoal tax returns, not corporate) will have three more days to file. An extension will will apply till Oct. 17, 2011.