Form 1065 and 1120-S late filing penalty calculator

For a partnership return required to be filed in 2026, it is $255 for each month or part of a month the return is late, up to 12 months, multiplied by the number of persons who were partners at any time during the tax year. The rate was $245 for returns due in 2025 and is $260 for returns due in 2027. It applies when the return is filed after the due date, extensions included, or is missing required information.

The same per-shareholder amount applies to Form 1120-S: $255 for each shareholder for each month or part of a month, up to 12 months, for returns due in 2026. If tax is due, the IRS adds a percentage of the unpaid tax for each month the return is late, so the total can be higher than this calculator shows.

A maximum of 12. Each month or part of a month counts as a full month, counted from the due date including any extension filed on time. A return one day late is one month late. A Form 7004 extension filed on time moves the due date out, so the clock starts later.

Yes. The IRS multiplies by everyone who was a partner, or a shareholder for an S corporation, at any time during the tax year the return covers. A person who joined or left mid-year is counted once, the same as someone who was there all year.

Sometimes. The IRS lists both penalties among those eligible for first-time abatement for a filer with three years of timely compliance, and it is moving that relief to an automatic exemption for 2025 returns and later, naming Form 1065 among the eligible returns. A filer who does not qualify can ask for relief for reasonable cause. The IRS decides, so file as soon as you can rather than waiting on a relief decision.

No. Failing to furnish a correct Schedule K-1 to a partner or shareholder on time has its own penalty, $340 per Schedule K-1 for statements due in 2026 and 2027. It is added on top of the late-filing penalty and is not included in this calculator.