It depends on how the LLC is classified for federal income tax purposes.

Single-member LLC (one owner), no corporate election

If a single‑member LLC has not elected to be taxed as a corporation, there is generally no separate federal income tax return required for the LLC itself, because it is treated as a disregarded entity and its income is reported on the owner’s return; however, if the LLC elects to be taxed as a C or S corporation, a separate corporate return (Form 1120 or 1120‑S) is then required.

If the owner is an individual, the business activity is generally reported on Form 1040. For calendar-year 2025 returns, Form 1040 is due April 15, 2026.

Multi-member LLC (two or more owners), no corporate election

A domestic multi-member LLC is generally classified as a partnership and files Form 1065.

Form 1065 is generally due by the 15th day of the 3rd month after the end of the tax year. For calendar-year 2025 returns, the due date is March 16, 2026, because March 15, 2026 falls on a Sunday.

LLC taxed as a C corporation

If the LLC elected to be taxed as a corporation, it generally files Form 1120.

Form 1120 is generally due by the 15th day of the 4th month after the end of the tax year. For calendar-year 2025 returns, the due date is April 15, 2026.

LLC taxed as an S corporation

If the LLC is eligible and made a valid S corporation election, it generally files Form 1120-S.

Form 1120-S is generally due by the 15th day of the 3rd month after the end of the tax year. For calendar-year 2025 returns, the due date is March 16, 2026, because March 15, 2026 falls on a Sunday.

Important related note

A corporation with a June 30 fiscal year end has a different federal due-date rule for Form 1120. Also, if the due date falls on a Saturday, Sunday, or legal holiday, the return is generally timely if filed on the next business day.

State Law Note

State income tax, franchise tax, annual report, and LLC fee filing deadlines are administered at the state level and may differ from the federal due dates above. The controlling authority is the applicable state revenue department or tax agency, and for entity-status filings, often the state business filing office.

Sources

IRS — Starting or ending a business 3

IRS — LLC Filing as a Corporation or Partnership

IRS — Single Member Limited Liability Companies

IRS — 2025 Instructions for Form 1065

IRS — Instructions for Form 1120-S (2025)

IRS — 2025 Instructions for Form 1120

IRS — Instructions for Form 1040 and Form 1040-SR (2025)

IRS — Publication 334, Tax Guide for Small Business (2025)

This information provided does not, and is not intended to, constitute legal advice.