As I previously discussed, the federal tax due date for partnership and corporate tax returns changed for tax years on or after 2016.  This means that the new filing deadlines are now in effect.  Partnership and S corporation tax returns are due a month earlier on March 15th, while corporate tax returns are now due a month later on April 15th.  In other words, you need to file any partnership or S corporation tax returns, or file for an extension, by Wednesday.