If your corporation, partnership or estate operates on a calendar year basis the tax return is due March 15th which is coming up! If you need additional time to file tax returns for these entities file IRS Form 7004 which is an application for Automatic Extension of Time To File Certain Business Income Tax, Information, and Other Returns.
Filing this form by March 15th gives you an additional 5 or 6 months to file your actual tax documents. Instructions for this form are essential so be sure to read them.
If you connect with me (or any tax practitioner worth their salt) to hit this deadline the first thing that you will be advised to do at this late date is to get this automatic extension request filed. If anything it alleviates the stress of rushing through the tax return AND you avoid the onerous late filing penalty.