If you file your taxes late, what are the penalties for doing so? Filing taxes and paying taxes are separate issues, so sometimes the penalty is nothing. The tax filing due date is April 15th, unless you ask for an extension until October 15th. If you owe no tax, you do not have to file, but you do give up any refunds that you might have been entitled to. Otherwise the penalty for not filing are standard late penalties and interest. For those who want more information on their specific tax situation, consider asking a tax professional for further advice.