What is Form 1065?

Who files it

Any US partnership — including every multi-member LLC that hasn't elected corporate taxation. Two members means a 1065, even between spouses in most states, even at a loss.

How the tax flows

The 1065 itself produces no tax bill. Each partner's share of income, deductions and credits rides a Schedule K-1 onto their personal return, where it's taxed at their rates. Foreign partners add withholding obligations for the partnership itself.

Deadline

March 15 for calendar-year partnerships, extendable to September 15. The late-filing penalty accrues per partner, per month — small partnerships rack it up fast without noticing.