The IRS and Maine Revenue Services are reminding Maine residents that they do not need to file their income tax returns until Tuesday, April 18. The IRS this year gave taxpayers an extra day because April 15, the traditional filing day, is on a Saturday. That pushed the date back to April 17, when post offices will be open again. In some states, including Maine, the deadline was pushed back to Tuesday because Monday is Patriots Day, a holiday in those states.