Florida’s Constitution bars a tax on the income of individual residents. It does not bar a tax on corporations, and Florida has one, under Chapter 220 of the Florida Statutes. For a Tampa business organized as a C corporation, that means two income tax returns every year: the federal Form 1120 and the Florida corporate return.

The Florida return is built on the federal one. So when the IRS audits the corporation and changes its federal taxable income, the Florida number changes too. Florida law requires the corporation to tell the state, and it gives a short deadline. Here is how that works and why it matters.

Florida starts with the federal number

Florida corporate income tax is computed starting from the corporation’s federal taxable income, with Florida-specific additions, subtractions and apportionment. The practical effect is simple: most changes the IRS makes to federal taxable income flow straight into Florida taxable income.

An IRS examiner who disallows $200,000 of deductions on a Tampa corporation’s Form 1120 has also, in effect, increased the corporation’s Florida starting point by $200,000.

For a corporation that does business in several states, Florida apportions its income, so only part of a federal change may end up taxed in Florida. A corporation that operates only in Hillsborough County typically has all of its business income apportioned to Florida, which means nearly every federal dollar of adjustment becomes a Florida dollar of adjustment. Florida-specific modifications can widen or narrow the effect, so the federal change is the starting point, not always the final answer. Either way, the change has to be reported and recomputed on the Florida side. The size of the Florida effect is a calculation. The duty to report it is not optional.

The reporting rule: Fla. Stat. 220.23

Fla. Stat. 220.23(2) sets special rules when a federal return is adjusted, whether by amendment or as a result of any other recomputation or redetermination of federal taxable income, and the adjustment would affect Florida net income.

Under 220.23(2)(a), the taxpayer must notify the Florida Department of Revenue of the adjustment by filing either an amended return or another report the Department prescribes. The filing must show the taxpayer’s name, address and employer identification number, the adjustments, the revised Florida net income and revised tax liability, and must be signed by a person required to sign the original return or an authorized representative.

The deadline is the important part. The filing is due not later than 60 days after the adjustment has been agreed to or finally determined for federal income tax purposes, or after any federal deficiency or refund resulting from it has been assessed, paid or collected, whichever occurs first.

The Department’s forms library lists Form F-1120X, Amended Florida Corporate Income/Franchise Tax Return with Instructions, for this purpose. Use the current version from the Department’s website.

What triggers the 60 days

The “whichever occurs first” language matters. Common triggers in an IRS case:

  • Signing an agreement form at the end of an examination.
  • The IRS assessing the agreed deficiency.
  • A Tax Court decision becoming final.
  • The corporation paying the federal deficiency.
  • The corporation filing an amended federal return that changes taxable income.

In many audits, the earliest trigger is the day the corporation agrees to the adjustments. Put the Florida deadline on the calendar that same day.

What happens if you report, and if you do not

Florida’s statute rewards reporting and punishes silence.

  • If you report and concede the federal change. Under 220.23(2)(b), any resulting Florida deficiency is deemed assessed on the date you file the amended return or report, and the assessment is timely regardless of the normal limitations period.
  • If you report. Under 220.23(2)(c)1., the Department may issue a notice of deficiency within 5 years after the notification is given, limited to the deficiency resulting from the items in the federal adjustment.
  • If you do not report. Under 220.23(2)(c)2., if the taxpayer fails to notify the Department or fails to report a change, a notice of deficiency may be issued at any time. The limitations period never starts.
  • Interest. Interest on a Florida deficiency runs from the original due date of the return, determined without extensions, until payment.

The “at any time” exposure is the real risk. A corporation that settles an IRS audit and quietly moves on can be revisited by Florida years later, with interest running the whole time.

Federal changes can help, too

Not every audit increases income. Sometimes the IRS allows a deduction the corporation missed, or an amended federal return reduces taxable income. Fla. Stat. 220.23(2)(d) lets the taxpayer file a Florida refund claim within 2 years after the date the notification was due, whether or not it was actually given, limited to the overpayment resulting from the federal adjustment. Miss that window and the Florida refund may be gone even though the federal one was allowed.

Under 220.23(1), the Department can also require a corporation to furnish copies of its federal returns relating to items at issue, at any time a Florida deficiency could be assessed or a refund claimed.

A sample timeline

Here is how the dates might line up for a hypothetical Tampa C corporation:

  • March: The IRS examination of the 2023 Form 1120 wraps up. The corporation agrees to adjustments disallowing certain deductions and signs the agreement form.
  • March plus 60 days: Under Fla. Stat. 220.23(2)(a)3., the Florida report is due, because agreement to the adjustment is the earliest trigger. The later IRS assessment does not restart the clock.
  • April: The IRS assesses the deficiency and the corporation pays it.
  • May: The corporation files its amended Florida return reporting the federal changes and pays the Florida tax and interest.

Because the corporation reported and conceded the federal changes, 220.23(2)(b) treats the Florida deficiency as assessed on the filing date, and 220.23(2)(c)1. limits the Department to the next five years for any deficiency notice tied to those items. If the corporation had done nothing, the Department could act at any time.

Notice what drove the deadline: not the IRS bill, but the corporation’s own signature on the agreement.

Coordinating the federal and Florida sides

A few habits keep a Tampa corporation out of trouble when the IRS comes calling:

  1. Think about Florida during the federal audit. Every federal concession has a Florida price. Factor it into settlement decisions. My guide on IRS audit representation in Tampa covers the federal process.
  2. Calendar the 60 days immediately after any agreement, assessment or final decision.
  3. File one clean Florida report covering all the federal changes, with the federal examination report attached or available.
  4. Budget for both. A corporation that can barely pay the federal deficiency also needs to plan for the Florida tax and interest. If it cannot pay, the Florida Department of Revenue has its own collection tools, including the bank freeze procedure in Fla. Stat. 213.67. See owing Florida and the IRS at the same time.

Individuals and pass-through owners

None of this applies to an individual’s personal return. Florida has no individual income tax, so an IRS audit of a Tampa resident’s Form 1040, including pass-through income from an S corporation or partnership, does not create a Florida income tax filing obligation. That is one of the genuine simplifications of living here, described in my guide on what Florida’s lack of an income tax changes.

C corporations are different, and the 60-day rule is the price of that difference. GetIRSHelp.com has more on handling IRS audits.

The IRS audit ends when you sign. The Florida clock starts at the same moment. Do not let the second one run out while you are celebrating the first.