{"id":25472,"date":"2026-10-29T12:43:56","date_gmt":"2026-10-29T12:43:56","guid":{"rendered":"https:\/\/maspartner.com\/?p=25472"},"modified":"2026-10-29T12:48:03","modified_gmt":"2026-10-29T12:48:03","slug":"business-tax-extension-deadlines","status":"publish","type":"post","link":"https:\/\/maspartner.com\/en-us\/blog\/business-tax-extension-deadlines\/","title":{"rendered":"Business Tax Extension Deadlines Explained: Form 1120, 1120-S and 1065"},"content":{"rendered":"

For calendar-year businesses, a timely Form 7004 extended the tax year 2025 filing deadline to September 15, 2026, for partnerships (Form 1065) and S corporations (Form 1120-S), and October 15, 2026, for C corporations (Form 1120). For tax year 2026, the corresponding extended deadlines are September 15 and October 15, 2027. A business tax extension gives you additional time to submit your return, but any tax owed must still be paid by the original deadline.<\/span>\u00a0<\/span><\/p>\n

This guide covers key filing dates for 2026 and 2027, Form 7004 requirements, payment rules, fiscal-year variations, and potential penalties.<\/span>\u00a0<\/span><\/p>\n

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<\/span>Business Tax Extension Due Dates for 2026 and 2027<\/span><\/span>\u00a0<\/span><\/span><\/h2>\n

Deadlines depend on the entity’s tax classification and accounting year. <\/span>This table compares original and extended deadlines for calendar-year businesses with valid extensions.<\/span><\/span>\u00a0<\/span><\/p>\n\n\n\n\n\n\n\n\n\n
Form<\/th>\nEntity<\/th>\nTax year<\/th>\nOriginal deadline<\/th>\nExtended deadline<\/th>\n<\/tr>\n<\/thead>\n
1065<\/td>\nPartnership<\/td>\n2025<\/td>\nMarch 16, 2026<\/td>\nSeptember 15, 2026<\/td>\n<\/tr>\n
1120-S<\/td>\nS corporation<\/td>\n2025<\/td>\nMarch 16, 2026<\/td>\nSeptember 15, 2026<\/td>\n<\/tr>\n
1120<\/td>\nC corporation<\/td>\n2025<\/td>\nApril 15, 2026<\/td>\nOctober 15, 2026<\/td>\n<\/tr>\n
1065 \/ 1120-S<\/td>\nPartnership \/ S corporation<\/td>\n2026<\/td>\nMarch 15, 2027<\/td>\nSeptember 15, 2027<\/td>\n<\/tr>\n
1120<\/td>\nC corporation<\/td>\n2026<\/td>\nApril 15, 2027<\/td>\nOctober 15, 2027<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n


\nFiscal-year entities follow different schedules. Sole proprietors (including single-member LLCs reporting on Schedule C) <\/span>generally use<\/span> Form 4868 instead. Calendar-year estates and trusts filing Form 1041 also use Form 7004, which provides a 5\u00bd-month extension, <\/span>generally to<\/span> September 30.<\/span><\/p>\n

<\/span>How Is the Six-Month Extension Period Measured?<\/span><\/span>\u00a0<\/span><\/span><\/h2>\n

A timely Form 7004 generally adds six months from the statutory filing deadline. Weekend and holiday rules can shift the original due date without changing the extended date.<\/span>\u00a0<\/span><\/p>\n

For example, March 15, 2026, was a Sunday, moving the original partnership and S corporation deadline to March 16. Their extension still ended September 15, 2026. See <\/span>IRS Publication 509<\/span><\/a> and the <\/span>Form 7004 instructions<\/span><\/a>.<\/span><\/p>\n

<\/span>Form 7004 Filing Instructions for Business Tax Extensions<\/span><\/span>\u00a0<\/span><\/span><\/h2>\n

Businesses filing Forms 1065, 1120-S, or 1120 <\/span>generally request<\/span> an automatic filing extension through Form 7004. Submit it by the original return deadline; electronic filing is available. A separate Form 7004 is <\/span>required<\/span> for each return.<\/span><\/p>\n

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  1. Identify the return:<\/span><\/b> Choose the appropriate form code and confirm the tax year-end.<\/span>\u00a0<\/span><\/li>\n
  2. Enter business details:<\/span><\/b> Provide the legal name, Employer Identification Number (EIN), and tax year.<\/span>\u00a0<\/span><\/li>\n
  3. Estimate and pay tax:<\/span><\/b> Calculate any outstanding liability and pay by the original deadline.<\/span>\u00a0<\/span><\/li>\n
  4. File and retain proof:<\/span><\/b> Submit Form 7004 and save the acknowledgment.<\/span><\/li>\n<\/ol>\n

    If the IRS rejects a timely e-filed Form 7004, you generally have five calendar days to correct and resubmit it and still have it treated as timely. Review IRS rejection notices promptly.<\/span>\u00a0<\/span><\/p>\n

    Our <\/span>Form 7004 filing guide<\/span><\/a> offers further instructions. The following sections cover the specific filing obligations and reporting rules for different business entities.<\/span>\u00a0<\/span><\/p>\n

    <\/span>When Do Partnerships and S Corporations Have to File?<\/span><\/span>\u00a0<\/span><\/span><\/h2>\n

    Partnerships filing Form 1065 and S corporations filing Form 1120-S generally have a March 15 deadline for calendar-year returns, extendable to September 15. Weekend and holiday adjustments may apply.<\/span>\u00a0<\/span><\/p>\n

    These entities generally pass income, deductions, and credits through to owners rather than paying federal income tax on all earnings at the entity level. Certain entity-level taxes can still arise. Timely filing also helps owners.<\/span><\/p>\n

    <\/span>How Does a Late Entity Return Affect the Owners?<\/span><\/span>\u00a0<\/span><\/span><\/h3>\n

    Partners and shareholders typically need Schedule K-1 to report their shares of business activity on individual returns. Delayed K-1s can prevent them from completing personal filings. Individual owners who need more time can request their own extension using Form 4868.<\/span>\u00a0<\/span><\/p>\n

    Organized <\/span>bookkeeping services<\/span><\/a> can support timely K-1s. See our <\/span>extension guide<\/span><\/a>.<\/span><\/p>\n

    <\/span>What Is the Extended Deadline for C Corporations Filing Form 1120?<\/span><\/span>\u00a0<\/span><\/span><\/h2>\n

    Calendar-year C corporations ordinarily file Form 1120 by April 15 and may extend the filing date to October 15 with Form 7004. Unlike pass-through entities, C corporations generally pay federal income tax at the corporate level.<\/span>\u00a0<\/span><\/p>\n

    <\/span>What Tax Is Due With Form 7004?<\/span><\/b>\u00a0<\/span><\/span><\/h3>\n

    C corporations pay federal income tax at a flat 21% rate. Corporations requesting an extension must estimate their liability, subtract payments already made, and pay any remaining amount by the original due date. The extension does not replace quarterly estimated tax requirements.<\/span>\u00a0<\/span><\/p>\n

    <\/span>What Changes for June 30 Fiscal-Year Corporations?<\/span><\/b>\u00a0<\/span><\/span><\/h3>\n

    Special transition rules apply to C corporations with a June 30 year-end. For tax years beginning before January 1, 2026, the return is due on the 15th day of the third month after year-end, and Form 7004 generally provides a seven-month extension. For tax years beginning on or after January 1, 2026, the standard C corporation rules apply: the return is due on the 15th day of the fourth month, with a six-month extension.<\/span>\u00a0<\/span><\/p>\n

    <\/span>How Do Fiscal-Year Businesses Calculate Their Extension Deadline?<\/span><\/b>\u00a0<\/span><\/span><\/h2>\n

    Fiscal-year businesses calculate deadlines from their own year-end.<\/span>\u00a0<\/span><\/p>\n

    <\/span>Counting Months From Year-End<\/span><\/b>\u00a0<\/span><\/span><\/h3>\n

    For a June 30, 2026 year-end, the original deadline is generally September 15, 2026, extended to April 15, 2027. For a June 30, 2027 year-end, the original deadline moves to October 15, 2027, extended to April 15, 2028. Check <\/span>IRS instructions<\/span><\/a>.<\/span>\u00a0<\/span><\/p>\n