Late Florida Corporate Income Tax Return (F-1120)

The short answer: A C corporation doing business, earning income or existing in Florida files Form F-1120 every year, even when it owes no Florida tax. A late return costs 10% of the unpaid tax for each month or part of a month, up to 50%; with no tax due, it’s $50 a month, up to $300. Interest runs on any tax paid late. To catch up, file each missing year in order, each one built from that year’s federal return.

Who has to file Form F-1120?

Every C corporation doing business, earning income or existing in Florida files, whether or not tax is due. That includes loss years and years when Florida income falls under the exemption. Other companies follow how they’re taxed federally:

S corporations file only for a year in which they pay federal income tax at the corporate level on Form 1120-S, such as the tax on excess net passive income or the built-in gains tax. Those mostly affect companies that were once C corporations.
LLCs taxed as corporations follow the rule for their tax type: every year if taxed as a C corporation, the S corporation rule if taxed as one. A disregarded single-member LLC doesn’t file its own F-1120; if a corporation owns it, its income goes on the corporation’s return.

One trap catches S corporations. Florida follows the federal status, and its instructions ask for the IRS notice accepting the election if the Department doesn’t have it. If the election was late or never accepted, the company is a C corporation for those years unless the IRS grants late-election relief, and “nothing to file in Florida” becomes missing F-1120s. See how relief for a late S corporation election works.

When is F-1120 due, and how does the extension work?

For a calendar-year company, the return is due May 1. The rule behind that date is the later of two deadlines:

the first day of the fifth month after the tax year ends (the fourth month for a June 30 year end in a tax year that began before 2026), or
the 15th day after the federal return’s original due date.

So a 2025 calendar-year return was due May 1, 2026. When a due date lands on a weekend or a federal or state holiday, a return postmarked the next business day is on time.

The extension form is F-7004, and it has to be filed, with the tentative tax paid, by the original due date. A federal extension alone doesn’t extend the Florida return. A valid extension lasts six months (seven months for a June 30 year end in a tax year that began before 2026), and only one is allowed per year. A calendar-year 2025 return on a valid extension is due November 2, 2026, because November 1 is a Sunday.

The extension gives more time to file, not to pay: interest runs from the original due date, and tax underpaid during the extension also draws a penalty of 12% a year. And it’s void if the tentative tax wasn’t paid, or was short by more than the greater of $2,000 or 30% of the tax on the return. A void extension leaves the return late from its original due date.

What does a late F-1120 cost?

The penalty depends on whether the return shows tax due. Under section 220.801 of the Florida Statutes:

With tax due: 10% of the unpaid tax for the first month or part of a month, and another 10% for each further month or part, up to 50% in total. Tax paid by the original due date, and credits allowed on it, don’t count toward that base.
With no tax due: $50 for each month or part of a month, up to $300 for each return. This penalty applies only when the corporation also had to file a federal return, and never on top of the percentage penalty for the same return.

Both penalties top out fast. The percentage penalty reaches its 50% cap once a return is more than four months late, and the no-tax penalty reaches $300 once it’s more than five months late. For a return a year or more overdue, the penalty has already stopped growing. Interest hasn’t.

A separate penalty applies to an incomplete return, one the Department can’t readily handle, verify or review, so a late return still has to be complete.

A company whose Florida tax for a year was more than $2,500 also had to make estimated payments during that year. Underpaying them adds a penalty of 12% a year, figured on Form F-2220.

How does Florida charge interest on late tax?

Interest runs on unpaid tax from the original due date, ignoring any extension, until the day it’s paid. The rate floats. By law it’s the six-month average prime rate, rounded to the nearest full percent, plus 4 percentage points. It’s recalculated for each January 1 and July 1, changes only when that figure differs from the rate in effect, and can never exceed 12% a year. For July 1, 2026 through December 31, 2026, the rate is 11% a year. Old unpaid tax is charged at each period’s rate in turn.

Florida doesn’t charge interest on interest. Filing stops the late-filing penalty from growing, where it hasn’t already hit its cap; paying the tax is what stops the interest.

How is the tax itself worked out?

The F-1120 starts from the company’s federal taxable income, and Florida adds and subtracts certain items. A company that also does business outside Florida then apportions the result to Florida (usually by property, payroll and sales); one that does business only in Florida doesn’t apportion. A $50,000 exemption comes off last.

The tax is 5.5% of what’s left for tax years that began before 2019 or in 2022 or later. Tax years that began in 2019, 2020 and 2021 used lower rates, so each old year is figured at its own year’s rate.

The exemption is prorated for a short tax year, and a controlled group of corporations shares one. A C corporation whose Florida income is no more than its exemption owes no Florida tax for that year. It still owes the return, and a late one draws the flat monthly penalty.

How do you catch up on missed F-1120s?

List the open years. A C corporation needs a return for every tax year after the last one filed. An S corporation checks each year’s Form 1120-S for corporate-level tax. If the company has a Department eServices login, it can view its filing history there.
Finish each federal return first. Every F-1120 starts from federal taxable income and has a copy of the federal return filed with the IRS attached. The year’s books are closed, the federal return is completed, and the F-1120 follows from the same numbers. If the federal returns are missing too, start with what to do about an unfiled Form 1120.
Use each year’s own form. Florida revises the F-1120 for each tax year, and its instructions warn that one year’s software can’t produce another year’s forms.
Work oldest to newest. Losses and overpayments carry forward, so each return feeds the next.
Tidy up the account. If the company has closed or sold, Florida’s instructions say to notify the Department at once. The “final return” box is checked only once the final federal return has been filed.

Waiting doesn’t close old years. When a required return was never filed, Florida law lets the Department assess the tax at any time. If the business disclosed the liability to the Department in writing before the Department contacted it, the usual three-year limit applies instead, but it counts from the later of the due date or the date the return is filed. Filing an old return starts that clock; it doesn’t close the year.

What can limit how far back Florida goes is its voluntary disclosure program, open to a business the Department hasn’t already contacted about the liability. The Department looks at the three years before the request’s postmark date, and state law lets it settle the tax and interest to those years. Its published policy is that once that tax and interest are paid, penalties are waived.

The program is open only until the Department makes contact, and late returns filed outside it face the penalties above, so it’s worth talking through with an attorney, a CPA or an enrolled agent before the first late return goes in.

After contact, penalties can still be settled or compromised when the Department decides the failure was due to reasonable cause and not willful neglect. That can be requested by you or an authorized representative, and it isn’t automatic. How the F-1120 fits with Florida’s other filings is on the Florida filings page.

Quick answers

Does a federal extension also extend the Florida return?

No. Only Form F-7004, filed with the tentative tax paid by the original due date, extends Form F-1120. Florida’s instructions say a copy of the federal extension alone won’t do it.

Does Florida charge interest on the late-filing penalty?

Only if the penalty isn’t paid within 20 days of the Department’s notice and demand, and then only from the date of that notice. Interest isn’t charged on interest.

Can an S corporation that used to be a C corporation owe Florida tax?

Yes. In a year it pays the federal built-in gains tax on assets it held as a C corporation, it files Form F-1120 and reports only the income taxed at the corporate level. Florida also doesn’t treat the last C corporation return before the election as a final return, so that return’s “final return” box stays unchecked.

Does a dormant C corporation still file Form F-1120?

Yes, as long as it still exists in Florida; existing there is enough to require the return. Filed late with no tax due, each one draws $50 a month, up to $300.

Cayde rebuilds the books for every missing year and gets each federal and Florida return filed together, so the numbers agree, at a fixed price agreed in writing first.

Sources

General information, not advice for your situation. Updated October 31, 2026.

Late Florida Form F-1120: who must file, what it costs and how to catch up