Final answer:
An automatic extension on a tax return for partnerships is six months, with the extended due date being September 15th.
Step-by-step explanation:
An automatic extension on a tax return for partnerships is six months. Partnerships are required to file Form 1065 by the original due date, which is March 15th. However, if they need more time to file their tax return, they can request an automatic extension, which gives them an additional six months to file. The extended due date for partnerships is September 15th.