15 March (calendar year) — 15th day of 3rd month after year-end.

Form 1065 — Partnership Return

Annual federal information return for partnerships and multi-member LLCs taxed as partnerships. Due 15 March for calendar-year filers. 6-month extension via Form 7004 to 15 September.

Who this applies to

  • Partnerships (general, limited, LLP)
  • Multi-member LLCs (default partnership taxation)
  • Joint ventures unless excluded from Subchapter K

What to file

Form 1065 with K-1 for each partner, P&L, balance sheet, M-1/M-2 reconciliations, partner basis schedules.

How to file

Electronically via authorized e-filers. Distribute K-1s to partners by 15 March.

Payment due

Partnership doesn't pay federal income tax. Partners pay on their K-1 share via personal Form 1040 (or partner-level corporate return).

Penalties for missing this deadline

Late filing: $245 per partner per month, max 12 months. CPAR (Centralized Partnership Audit Regime) since 2018 means partnership-level adjustments can be assessed at entity level.

Filing checklist

  • Reconcile book income to ordinary business income
  • Calculate guaranteed payments to partners
  • Update each partner's capital account and basis
  • Generate K-1 for each partner
  • File electronically
  • Distribute K-1s by 15 March

Common mistakes to avoid

  • Treating LLC as corporation by accident (default is partnership for multi-member)
  • Missing K-1 distribution deadline
  • Not tracking inside vs outside basis for partners
  • Forgetting state partnership tax / withholding for non-resident partners

Never miss a United States deadline

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