P>Technically, you do not have to file or pay your taxes at the time of filing an extension. However, if you do not pay the tax that is due at that point in time, it does not alleviate the tax liability or any estimated penalties for that tax. For instance, if you owed a thousand dollars on April fifteenth and a thousand dollars was the tax due on October 15, you would have to pay the tax plus any penalties and interest associated with that due to the failure to pay the tax at the time of the extension.