--- title: "Business tax deadlines and extension dates | Ledgerbrook" source: https://ledgerbrook.com/blog/business-tax-deadlines/ description: "Tax extension due dates for 2027 by entity type: each return's filing date, extended date, and when the books must be closed." --- [Blogs](/blog/) # Business tax deadlines and extension dates ![](/_astro/omkar-moraye.BHiWb4KG_xH3b5.webp) [Omkar Moraye](/about/) · October 19, 2026 · Updated October 23, 2026 [](https://www.linkedin.com/sharing/share-offsite/?url=https%3A%2F%2Fledgerbrook.com%2Fblog%2Fbusiness-tax-deadlines%2F%3Futm_source%3Dlinkedin%26utm_medium%3Dsocial%26utm_campaign%3Dshare)[](https://x.com/intent/post?url=https%3A%2F%2Fledgerbrook.com%2Fblog%2Fbusiness-tax-deadlines%2F%3Futm_source%3Dx%26utm_medium%3Dsocial%26utm_campaign%3Dshare&text=Business%20tax%20deadlines%20and%20extension%20dates)[](https://www.facebook.com/sharer/sharer.php?u=https%3A%2F%2Fledgerbrook.com%2Fblog%2Fbusiness-tax-deadlines%2F%3Futm_source%3Dfacebook%26utm_medium%3Dsocial%26utm_campaign%3Dshare)[](mailto:?subject=Business%20tax%20deadlines%20and%20extension%20dates&body=Business%20tax%20deadlines%20and%20extension%20dates%0A%0Ahttps%3A%2F%2Fledgerbrook.com%2Fblog%2Fbusiness-tax-deadlines%2F%3Futm_source%3Demail%26utm_medium%3Dsocial%26utm_campaign%3Dshare) ## When are business tax returns due? For the 2026 tax year, partnerships and S corps file by March 15, 2027 and can extend to September 15. Sole proprietors on Schedule C and C corporations file by April 15 and can extend to October 15. An extension moves the filing date, not the payment date, and the preparer needs closed books first. Tax extension due dates depend on what kind of business files the return, and most owners only find that out when the preparer asks for the books. A partnership and an S corporation are due a month before a C corporation or a sole proprietor, and their extended date is a month earlier too. The October 15 date most people know is only the extended date for individuals and C corporations. The dates below are for a calendar-year business filing its 2026 return in 2027, worked out from the IRS rules and checked for weekends and federal holidays. The IRS publishes the 2027 edition of its tax calendar, Publication 509, around the end of the year, and this page is checked against it then. Ledgerbrook keeps books and does not file returns, so for anything about your own return, ask the CPA or enrolled agent who prepares it. ## Tax extension due dates for 2027, by entity type | Business | Return | Due | Extension form | Extended due | Books closed by | | --- | --- | --- | --- | --- | --- | | Partnership, multi-member LLC | 1065 | Mar 15, 2027 | 7004 | Sep 15, 2027 | Feb 15, 2027 | | S corporation, LLC taxed as an S corp | 1120-S | Mar 15, 2027 | 7004 | Sep 15, 2027 | Feb 15, 2027 | | C corporation, LLC taxed as a C corp | 1120 | Apr 15, 2027 | 7004 | Oct 15, 2027 | Mar 15, 2027 | | Sole proprietor, single-member LLC (no election) | 1040, Schedule C | Apr 15, 2027 | 4868 | Oct 15, 2027 | Mar 15, 2027 | | Tax-exempt organization | 990 or 990-EZ | May 17, 2027 | 8868 | Nov 15, 2027 | Apr 15, 2027 | The rules behind the dates, from the IRS instructions for each form: - **Partnerships and S corporations** file by the 15th day of the 3rd month after the tax year ends ([Instructions for Form 1065](https://www.irs.gov/instructions/i1065); [Instructions for Form 1120-S](https://www.irs.gov/instructions/i1120s)). - **C corporations and individuals** file by the 15th day of the 4th month ([IRS Publication 509](https://www.irs.gov/publications/p509)). - **Tax-exempt organizations** file by the 15th day of the 5th month ([IRS annual filing requirements](https://www.irs.gov/charities-non-profits/exempt-organization-annual-filing-requirements-overview)). May 15, 2027 is a Saturday, so the 990 moves to Monday, May 17. - **Weekends and holidays.** A due date that falls on a Saturday, Sunday or legal holiday moves to the next business day. In 2027 the March, April, September and October dates all fall on weekdays. A business with a fiscal year counts the months from its own year end instead. C corporations with a June 30 year end had a 7-month extension for tax years beginning before 2026; for tax years beginning in 2026 it is 6 months, like everyone else ([Instructions for Form 7004](https://www.irs.gov/instructions/i7004), revised December 2025). ### What the “books closed by” column means The IRS sets the first five columns. The last one is ours: about four weeks before the filing date, so the preparer has the closed year with time to work on the return. It is a planning target, not an IRS rule, and a busy practice may ask for the books earlier, so ask your preparer for their own cutoff. “Closed” means every bank and card account is reconciled through December 31, the holding accounts are cleared, payroll and 1099 totals tie, and the year is locked in QuickBooks so nobody changes it after the numbers go to the CPA. That work, in order, is the [year-end bookkeeping checklist](/blog/year-end-bookkeeping-checklist/). ### Why partnerships and S corps come first A partnership or S corporation does not pay income tax itself. Its income passes through to the owners on Schedule K-1, and each owner needs that K-1 to file a personal return due April 15. The K-1 is due to the owners by the date the business return is due, including any extension (the Instructions for [Form 1065](https://www.irs.gov/instructions/i1065) and [Form 1120-S](https://www.irs.gov/instructions/i1120s)). A partnership that extends to September 15 often pushes its owners into extending their own returns to October 15. Books not closed for 2026, and a March or April deadline coming? That is a cleanup, not a one-off fix: $99 per month of backlog (20% off 6+ months), one fixed price agreed before any work starts. [Send the file for a free 48-hour review](/contact/?from=blog%2Fbusiness-tax-deadlines). ## The October tax extension due date The October tax extension due date for most returns filed in 2026 was **Thursday, October 15, 2026**: it was the last day to file a 2025 individual return, Schedule C included, or a calendar-year C corporation return on extension. The next one is **Friday, October 15, 2027**, for 2026 returns. There is no second extension. The automatic extension for each of these returns is 6 months, and once it runs out the return is late ([Instructions for Form 7004](https://www.irs.gov/instructions/i7004)). If a 2025 return is still not filed after October 15, file it as soon as possible: the failure-to-file penalty grows each month the return is late. Partnerships and S corporations on a calendar year were already due on extension on September 15, 2026. ## An extension moves the filing date, not the payment date This is the part of an extension that costs money. Form 7004 “does not extend the time to pay any tax due,” and any balance has to be paid by the original due date of the return ([Instructions for Form 7004](https://www.irs.gov/instructions/i7004)). Interest runs on unpaid tax from the regular due date “even if you have been granted an extension,” and a late-payment penalty of ½ of 1% a month applies, up to 25% of the unpaid tax. How each extension is requested: | Return | Extension form | How | | --- | --- | --- | | 1065, 1120-S, 1120 | Form 7004 | One Form 7004 per return, filed by the regular due date, on paper or electronically | | 1040 with Schedule C | Form 4868 | Form 4868 by April 15, or an online payment marked as an extension payment, which needs no separate form | | 990, 990-EZ | Form 8868 | One Form 8868 per return, filed by the original due date, for an automatic 6-month extension | For individuals, the IRS says that paying online and checking the box that the payment is for an extension counts as the extension request ([get an extension to file your tax return](https://www.irs.gov/filing/get-an-extension-to-file-your-tax-return)). There is no equivalent for the business returns: Form 7004 has to be filed. ### Is there a penalty for filing an extension? No. An extension filed on time carries no penalty. The costs come from tax that was not paid by the original due date, and from a return filed after the extended date. ### Is there a downside to filing a tax extension? The extension itself has none. In practice there are three: - **The tax is still due on the original date.** Someone has to estimate it from books that are not finished, and an estimate that is too low starts interest and the late-payment penalty on the difference. - **Pass-through owners wait.** A partnership or S corp on extension delays every owner’s K-1, and with it their personal returns. - **Lenders and grant programs ask for a filed return.** A loan application that needs last year’s return will wait until September or October. ## What happens if business taxes are late The penalties differ by return type. These are the IRS figures for returns due in 2026; the dollar amounts are adjusted for inflation each year. | Return | Late filing | Late payment | | --- | --- | --- | | 1040 (Schedule C), 1120 | 5% of unpaid tax per month, up to 25%; if more than 60 days late, at least $525 or 100% of the tax, whichever is less | ½% of unpaid tax per month, up to 25% | | 1065 | $255 per partner for each month late, up to 12 months | No entity-level income tax | | 1120-S | $255 per shareholder for each month late, up to 12 months, plus 5% a month of any tax due, up to 25% | ½% of unpaid tax per month, up to 25% | Sources: the IRS [failure-to-file penalty](https://www.irs.gov/payments/failure-to-file-penalty) page, read October 19, 2026, and the Instructions for [Form 1065](https://www.irs.gov/instructions/i1065) and [Form 1120-S](https://www.irs.gov/instructions/i1120s) for 2025. When both penalties apply to the same month, the failure-to-file penalty is reduced by the failure-to-pay penalty for that month. The partnership penalty is the one that surprises owners. It is charged even when the partnership owes no tax at all, and it multiplies by headcount: a four-partner LLC that files three months late is looking at 4 × 3 × $255, or $3,060. Separate penalties apply to K-1s furnished late. Each penalty can be removed for reasonable cause, which is a question for your preparer. If several years are unfiled rather than one, the books for each year come first; the order to rebuild them in is in [behind on business taxes](/blog/behind-on-business-taxes/). ## Estimated tax payment dates for 2027 Estimated payments run on their own calendar, separate from the return and unaffected by an extension. | Installment | Individuals (sole proprietors, partners, S corp owners) | C corporations | | --- | --- | --- | | 1st | Apr 15, 2027 | Apr 15, 2027 | | 2nd | Jun 15, 2027 | Jun 15, 2027 | | 3rd | Sep 15, 2027 | Sep 15, 2027 | | 4th | Jan 18, 2028 | Dec 15, 2027 | The rule is the 15th day of the 4th, 6th and 9th months of the year, then the 1st month after it ends for individuals and the 12th month for corporations ([Publication 509](https://www.irs.gov/publications/p509)). January 15, 2028 is a Saturday and Monday, January 17 is Martin Luther King Jr. Day, so the last individual payment for 2027 is due Tuesday, January 18, 2028. The last 2026 payment is due Friday, January 15, 2027. For a sole proprietor, partner or S corp owner these payments are personal income tax, even when they come out of the business account. Where they belong in QuickBooks Online is in [recording estimated tax payments](/fixes/estimated-tax-payments/). ## The deadlines before the returns The returns above depend on forms with earlier dates. W-2s and 1099-NECs for 2026 are due **Monday, February 1, 2027**, with no automatic extension, because January 31 is a Sunday. Those dates, with the payroll returns, are in the year-end checklist; who needs a 1099 at all is in [when to send a 1099](/blog/when-to-send-a-1099/). State returns follow their own calendars. Some states accept the federal extension and others require their own form, so check with your state’s revenue department before relying on Form 7004 or 4868 for the state return too. ### Will the IRS extend the 2026 deadline? Only for specific places. When a federally declared disaster hits an area, the IRS postpones filing and payment deadlines for taxpayers there, sometimes by months. The postponements are listed on the IRS [tax relief in disaster situations](https://www.irs.gov/newsroom/tax-relief-in-disaster-situations) page by state. There is no general extension for everyone. ## Common questions about business tax deadlines ### What is the tax extension deadline for LLCs? It depends on how the LLC is taxed, not on its being an LLC. A single-member LLC with no election files on the owner’s Schedule C: due April 15, 2027, extended to October 15 with Form 4868. A multi-member LLC files Form 1065: due March 15, extended to September 15 with Form 7004. An LLC that elected S or C corporation treatment follows the 1120-S or 1120 row of the table. ### Do businesses have to file taxes by March 15? Only partnerships, multi-member LLCs and S corporations on a calendar year. C corporations and sole proprietors file by April 15. Any of them can extend, but the tax is still due on the original date. ### What is the S corp tax deadline? Form 1120-S for 2026 is due March 15, 2027. With Form 7004 filed by that date, it extends to September 15, 2027. Shareholders’ K-1s are due on the same dates. ### What is the deadline for corporate tax returns? A calendar-year C corporation files Form 1120 for 2026 by April 15, 2027, or by October 15, 2027 with Form 7004. Its fourth estimated payment for 2027 is due December 15, 2027. ### Can I still file a business tax extension? Not for a calendar-year 2025 return: the extension had to be filed by the original due date, March 16 or April 15, 2026. For the 2026 returns, Form 7004 or Form 4868 has to be filed by the original due date: March 15 or April 15, 2027. ## When the books are not closed in time An extension buys six months to file. It does not buy time for a business that has no books at all: the tax payment is still due in March or April, and nobody can estimate it from twelve unentered months of bank statements. If the year is not in QuickBooks by mid-February, the realistic options are a catch-up before the original date or an extension with a payment estimated from incomplete figures. How long the first option takes, by months behind, is in [how long catch-up bookkeeping takes](/blog/how-long-does-catch-up-bookkeeping-take/). $99per month of backlog20% off 6+ months > **When to hand this off:** if more than two months of 2026 are unreconciled on February 1, the March 15 date is already tight for a partnership or S corp. Send the file for a [free file review](/contact/?from=blog%2Fbusiness-tax-deadlines) and you get the month count and a fixed price back before any work starts. What a catch-up covers is on the [catch-up bookkeeping](/quickbooks-catch-up-bookkeeping/) page. Ledgerbrook Behind on your QuickBooks books? Cleanup or catch-up $99 per month of backlog, 20% off 6+ months Turnaround 5 business days for a typical year Monthly close From $99 a file a month [Get a free file review](/contact/?from=blog%2Fbusiness-tax-deadlines) Free, no card, no obligation. A written answer within about 48 hours. [See every price](/pricing/) [![](/_astro/omkar-moraye.BHiWb4KG_2p9N2A.webp)Omkar MorayeQuickBooks Certified ProAdvisor](/about/) - [![Intuit QuickBooks Certification Level 1](/_astro/level-1.BokmyvzE_Z2cyGo6.webp)](https://www.credly.com/badges/7ceaf1c4-83da-4a1b-b19f-7e15cb5c0ac7/public_url "Intuit QuickBooks Certification Level 1. Verify on Credly.") - [![Intuit QuickBooks Certification Level 2](/_astro/level-2.D-GWLUNI_Z1Sh5RD.webp)](https://www.credly.com/badges/02426568-00bb-46e1-a939-9063497c54d6/public_url "Intuit QuickBooks Certification Level 2. 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