If I'm starting a small partnership, when are the tax returns due if I have a calendar year end? What are the penalties for filing late? Someone told me you never want to file tax returns late - why is that? Thanks in advance.
From the IRS instructions for Form 1065 (partnership return):
Generally, a domestic partnership must file Form 1065 by the 15th day of the 4th month following the date its tax year ended as shown at the top of Form 1065.
Filing late will potentially lead to a penalty from the IRS. There's also the general point of not wanting to draw bad attention to yourself. Also from the instruction for Form 1065:
A penalty is assessed against the partnership if it is required to file a partnership return and it (a) fails to file the return by the due date, including extensions or (b) files a return that fails to show all the information required, unless such failure is due to reasonable cause. The penalty is $195 for each month or part of a month (for a maximum of 12 months) the failure continues, multiplied by the total number of persons who were partners in the partnership during any part of the partnership's tax year for which the return is due. If the partnership receives a notice about a penalty after it files the return, the partnership may send the IRS an explanation and the Service will determine if the explanation meets reasonable-cause criteria. Do not attach an explanation when filing the return.