Key takeaways
- Tennessee taxes the corporation, not just the shareholders: the federal S election does not remove the state franchise and excise return.
- For a calendar-year 2026 return, the state return and payment are due April 15, 2027, a full month after Form 1120-S.
- The state extension is seven months, but it only holds if enough tax is paid by April 15.
- Collect the federal return, the balance sheet and the prior-year state return before anyone starts the state calculation.
The two returns an S corporation files
The federal return is Form 1120-S, with a Schedule K-1 for each shareholder. It reports income, but the corporation generally owes no federal income tax on it, so the main consequence of getting it late is the per-shareholder penalty covered below.
The state return is the Tennessee franchise and excise tax return, filed through the Department's online system or on its paper form. The Department of Revenue says corporations, limited partnerships, limited liability companies and business trusts that are chartered, qualified, registered or doing business in Tennessee must register for and pay franchise and excise taxes. An S corporation is still a corporation under that rule, so the federal election does not exempt it.
Before building the engagement letter, confirm which entity the client really is. A Tennessee LLC taxed as an S corporation for federal purposes is an LLC for the state, and the state return follows the legal entity, not the federal tax label.
How the state tax is computed
There are two taxes on one return. The excise tax is 6.5% of Tennessee taxable income, and it starts from net earnings. The franchise tax is 0.25% of Tennessee net worth, which the Department describes as total assets less total liabilities. The minimum franchise tax is $100, and it applies whether or not the company is active.
Worked example: an S corporation has $300,000 of Tennessee taxable income and $400,000 of Tennessee net worth. Excise is 6.5% of $300,000, or $19,500. Franchise is 0.25% of $400,000, or $1,000. The return shows $20,500 before credits and prior payments. A dormant corporation with no income still owes the $100 minimum.
The net worth side is why the balance sheet matters here. Shareholder loans, accumulated retained earnings and distributions all move net worth, so a bookkeeper who has not reconciled equity will produce a wrong franchise number even when the income is right. Confirm the current-year schedules and any 2024 changes to the net worth base in the Department's instructions before preparing.
Due dates for tax year 2026
The state return is due the 15th day of the fourth month after the close of the books and records, which is April 15, 2027 for a calendar-year corporation. The tax is due with the return.
Form 1120-S for a calendar-year corporation is due March 15. The 2025 instructions note that the 2026 date moved to March 16, 2026 because March 15th fell on a Sunday. For tax year 2026 the federal date is March 15, 2027, which is a Monday. Plan the federal return first, because the state calculation starts from it.
If the corporation has a fiscal year, both dates move with the year end. The state rule counts four months from the close of the books, so a June 30 year end has a state due date of October 15.
Extensions and the payment trap
The federal extension is Form 7004, which requests an automatic 6-month extension of time to file and is filed by the regular due date of the return. It extends the filing date, not the date for paying tax.
Tennessee grants a seven-month extension. The statute conditions it on a request by the original due date and a payment of at least the lesser of 90% of the current-year liability or 100% of the tax shown on the prior-year return. If there was no prior-year liability, the payment must equal the minimum tax. A shortfall brings penalties and interest as though no extension existed. Statute text was read on a secondary legal site, so confirm the wording on the Department's extension page.
Worked example: the 2026 liability turns out to be $20,500 and the 2025 return showed $15,000. The lesser of 90% of $20,500 ($18,450) and $15,000 is $15,000. Paying $15,000 by April 15, 2027 protects the extension, and the $5,500 balance is still due, with interest, when the return is filed.
Message to send the client: "To extend your Tennessee return we need a payment by April 15, 2027. Based on last year's return the amount is $15,000. Please confirm you can fund it by the end of March." Keep the reply in the file.
Estimated payments
Tennessee requires estimated payments on the 15th day of the fourth, sixth and ninth months of the tax year, plus the first month of the next year, when combined liability was $5,000 or more in both the prior and current years. For a calendar-year corporation those are April 15, June 15, September 15 and January 15.
A corporation at $20,500 of liability is well past that line, so it should have been paying all year. Check the client's payment history in the Department's online system before the return is prepared and use it as the credit figure rather than the client's memory.
Shareholders, withholding and composite returns
In the Department's franchise and excise materials I reviewed, I found no composite return or nonresident shareholder withholding program for S corporations comparable to what many states run. Treat that as a finding to confirm against the current instructions, not as a rule.
The question still matters for out-of-state shareholders. Ask where each shareholder lives and whether that state requires composite filing, withholding or a pass-through entity tax election by the corporation. The shareholder's home state, not Tennessee, usually drives that work, and the answer belongs in the engagement file. Decision rule: if a shareholder lives outside Tennessee, get the home-state filing requirement before April 15, 2027; if every shareholder lives in Tennessee, no shareholder-state work arises.
Tennessee also offers an obligated member entity election, but the Department's materials describe it for LLCs, limited partnerships and limited liability partnerships, and it requires every member to elect. A corporation filing as an S corporation should not count on it.
Federal penalties when the S corporation is late
A late Form 1120-S costs $255 per month or part of a month, up to 12 months, multiplied by the number of shareholders. With tax due, add 5% of the unpaid tax per month, capped at 25%. For returns required to be filed in 2026 that are more than 60 days late, the minimum penalty is the smaller of the tax due or $525.
Example: a three-shareholder S corporation files four months and two days late with no tax due. That is five months or parts of months, so 5 x 3 x $255 = $3,825. The state side adds its own penalty and interest, so a missed March date can become two separate notices.
What to collect from the client
Send one request covering both returns, dated well ahead of March 15, 2027. Ask for: the filed 2025 Form 1120-S and Tennessee return with payment confirmations; the 2026 year-end balance sheet with equity roll-forward; a shareholder list with state of residence, ownership percentages and any changes during 2026; and loan, distribution and basis records for each shareholder.
Add the items that only surface in conversation: officer pay for Form 1125-E, which is required when receipts are $500,000 or more, any Tennessee-versus-other-state revenue breakdown, and notices from the Department of Revenue. If the S election itself is in doubt, pull the Form 2553 acceptance letter, since it generally must be filed no more than 2 months and 15 days after the beginning of the year the election starts.
Usual can send this list as a request with a due date and reminders, and clients upload files through a secure link instead of email. It does not prepare the return.