Key takeaways
- The federal Form 1120-S for a 2026 calendar-year return is due March 15, 2027, according to the 2025 instructions.
- Form 7004 extends only the federal return. New York uses Form CT-5.4, and every other state needs its own check.
- Texas franchise tax report is due May 15, and an entity at or below $2,650,000 for report years 2026 and 2027 still files an information report.
- New York Form CT-3-S and Illinois Form IL-1120-ST both use March 15 for a calendar-year return. Tennessee's F&E figures stay open.
Start with the federal Form 1120-S date
A calendar-year S corporation files Form 1120-S. The instructions for Form 1120-S say the return is due by the 15th day of the 3rd month after the end of the tax year. For a 2026 calendar-year return, that is March 15, 2027. These are the 2025 instructions, so check the 2026 revision.
The 2025 return followed a different date. The same instructions give March 16, 2026 for calendar-year corporations, because March 15, 2026 fell on a Sunday. Set the date from the tax year of the return, not from the year you are working in.
The automatic extension is Form 7004. The instructions say the corporation generally must file Form 7004 by the regular due date of the return. Form 7004 is federal only. It does not extend any state return, so each state row needs its own check.
Build the state map before the return starts
Build one row per state for each entity. Each row needs five fields: whether the state taxes the entity or only the owners, the state form name, the due date for a calendar-year filer, the minimum or fixed tax, and the extension form. Write the page address and the date you read each field next to it.
Decision rule: if the S corp has receipts, property or employees in a state, add that state to the list even when the owners live somewhere else. Then read that state's entity return rules before the client is told which returns are needed.
The four states side by side
Tennessee: franchise and excise tax (F&E), an entity-level tax. The rates, minimum and due date could not be confirmed, so those cells stay open until the Department of Revenue page is read.
Texas: franchise tax report, due May 15. The no-tax-due threshold is $2,650,000 for report years 2026 and 2027. An entity at or below the threshold still files an information report, the Public Information Report or the Ownership Report.
New York: Form CT-3-S, New York S Corporation Franchise Tax Return. The 2023 instructions give a March 15 due date for a calendar-year return, a fixed dollar minimum from $25 to $4,500 tied to New York receipts, and Form CT-5.4 as the six-month extension.
Illinois: Form IL-1120-ST, Small Business Corporation Replacement Tax Return, due on or before March 15 for a calendar-year return. The page read states no fixed minimum or extension form; the rate comes from the Tax Rate Database.
Tennessee: franchise and excise tax (F&E) is an open row
Tennessee taxes an S corporation at the entity level through the franchise and excise tax, shortened to F&E. An S corp with Tennessee activity needs its own F&E row, separate from the federal return and from any owner-level filing.
This guide did not confirm Tennessee's excise rate, franchise rate, minimum or due date. The Department of Revenue due-date and rates page returned HTTP 403 on every fetch when it was checked on 2026-11-09. Do not fill those cells from memory or from a vendor summary.
Fix: open the Department page, copy the excise rate, franchise rate, calendar-year due date and any minimum into the file with the date read, then compare the due date with March 15 rather than assuming a match.
Texas: franchise tax report and the no-tax-due threshold
The Texas franchise tax applies to each taxable entity formed or organized in Texas or doing business in Texas, per the Comptroller's page. Check the entity type before deciding an S corp is in scope or out.
The annual franchise tax report is due May 15. If May 15 falls on a weekend or holiday, the due date moves to the next business day.
The no-tax-due threshold is $2,650,000 for report years 2026 and 2027. The same page lists $2,470,000 for 2024 and 2025. An entity at or below the threshold owes no franchise tax, but the page says it still files a report: the 2026 Public Information Report or Ownership Report. Tell the client an information report is due, not that nothing is due.
Decision rule: pull total revenue for the report year, compare it with the threshold for that year, and write the result and the page address in the file.
New York: Form CT-3-S and the fixed dollar minimum
New York S corporations file Form CT-3-S, New York S Corporation Franchise Tax Return, instead of Form CT-3 or Form CT-3-A. The Department says the form applies to a business that elected New York S status by filing Form CT-6, or that is a mandated New York S corporation. Confirm which applies before choosing the form.
The 2023 CT-3-S instructions say a calendar-year return is due on or before March 15. The 2025 PDF could not be read, so confirm both the due date and the minimum against the current instructions before the calendar is set.
The 2023 instructions set the fixed dollar minimum by New York receipts. The lowest tier is $25 for receipts of $100,000 or less. The tiers step up to $50, $175, $300, $1,000 and $3,000, and the highest tier is $4,500 for receipts over $25,000,000. Find New York receipts for the year, pick the tier, and confirm the amount in the current instructions.
For more time, the extension is Form CT-5.4, Request for Six-Month Extension to File New York S Corporation Franchise Tax Return. Do not use the federal Form 7004 for New York, and do not use Form CT-5.3, which the Department describes as the combined-return extension.
Illinois: replacement tax on Form IL-1120-ST
Illinois taxes S corporations through the replacement tax. The Department of Revenue says S corporations are subject to replacement tax, but do not pay Illinois income tax. The return is Form IL-1120-ST, Small Business Corporation Replacement Tax Return.
Form IL-1120-ST is due on or before the 15th day of the 3rd month following the close of the tax year. For a 2026 calendar year, that is March 15, 2027, the same day as the federal return.
Decision rule: if the S corp has Illinois net income, add IL-1120-ST to the state list with the March 15 date, and pull the replacement tax rate from the Department's Tax Rate Database.
What this version does not cover
This version covers the federal return, Texas, New York and Illinois, and names Tennessee without confirmed numbers. California, New Jersey and the other states are not included, because they were not checked here and are left out rather than filled in from memory.
Decision rule: if the client does business in a state not in this guide, the federal March 15, 2027 date is only the federal date. Hold that state's row open until its due date and minimum are written from the state's own page.
Failure modes and fixes
Failure: one March date is used for every state. Fix: give each state its own row. Texas is due May 15, so a single March entry misses it.
Failure: a Texas client is treated as exempt because revenue is under $2,650,000. Fix: the threshold decides whether franchise tax is owed, not whether a report is due. Put the Public Information Report in the file for that client and check the filing requirement on the Comptroller's site.
Failure: the New York extension is requested on the federal Form 7004. Fix: file Form CT-5.4 for the CT-3-S, and calendar the return from the New York instructions rather than the federal date.
Failure: a vendor summary gives a minimum or due date that does not match the state. Fix: quote the state page in the file with the date you checked it, and correct the summary before the client letter goes out.