Partnership penalty and interest calculator
A late Form 1065 costs a monthly penalty for every partner. Enter the number of partners and the dates, and add any tax the partnership itself owes, such as foreign partner withholding.
Prepared by Prem Tax and Accounting Corp. Last checked against official sources on November 11, 2026.
How the estimate works
- Late filing, per partner: partners times $255 (the 2026 amount) times months late, part of a month counted, up to 12 months.
- Entity-level tax: 0.5% a month late-payment penalty, up to 25%, plus daily interest at the IRS underpayment rate.
We file partnership returns and request relief for late ones. Book a 10-minute call.
Common questions
Does the penalty depend on tax due?
No. A partnership usually owes no income tax, and the penalty is charged for each partner for each month the return is late, up to 12 months.
Can the penalty be removed?
Often. Small partnerships (generally 100 or fewer partners, all individuals) can qualify for relief under Revenue Procedure 84-35, and reasonable cause applies to any partnership.
What is entity-level tax?
Tax the partnership itself pays, for example withholding on foreign partners or an imputed underpayment under the centralized partnership audit rules. It gets late-payment penalties and interest.
Official sources
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