Harper Tax CPA

Filing an S Corporation Late: IRS & Arizona Penalties Explained

Missing the S-corporation filing deadline can be an expensive mistake — especially if you operate in Arizona and have an S-corp or an LLC taxed as an S-corp.

In this guide, we’ll walk through:

  • What “filing an S-corporation late” actually means
  • IRS late-filing penalties for Form 1120-S
  • Arizona Department of Revenue (ADOR) penalties for late Form 120S
  • The difference between a late S-corp tax return and a late S-election
  • What you can do now if your S-corp is already late

Disclaimer: Penalty amounts change periodically due to law changes and inflation adjustments. Always confirm with the latest IRS and Arizona Department of Revenue instructions or work with a CPA for your specific situation.

1. What Does “Filing an S Corporation Late” Mean?

When people say they “filed an S-corp late,” they might be talking about several different issues.

Late S-corporation tax return

Federal (IRS)
Form 1120-S filed after the due date — generally the 15th day of the 3rd month after year-end (March 15 for calendar-year S-corps, or the next business day), or after the extended due date if you filed a valid extension.

Arizona (ADOR)
Form 120S (Arizona S Corporation Income Tax Return) filed after the Arizona due date — generally the 15th day of the 3rd month after the end of the tax year (mid-March for calendar-year S-corps), or after the extended due date if you filed a valid extension.

Note: For calendar-year S-corps, federal 1120-S and Arizona 120S share the same general due month (March), though the exact date can shift to the next business day.

Late S-corporation election (Form 2553)

Form 2553 was not filed on time, so the IRS may not treat the company as an S-corporation for that year unless late-election relief is granted.

Late payment of tax

Federal
Less common at the S-corp level, because income typically passes through to shareholders — but it can arise from items like built-in gains tax, excess net passive income tax, or other corporate-level taxes.

Arizona
Arizona generally conforms to federal S-corporation treatment — most S-corp income passes through to shareholders. However, an S-corp can also elect into Arizona’s Pass-Through Entity (PTE) tax, which is an entity-level tax at a flat rate (currently 2.5%) on certain S-corp income for participating owners.

This article focuses mainly on late tax returns and late payments for the IRS and Arizona.

2. IRS Late Filing Penalties for S Corporations (Form 1120-S)

A. Per-Shareholder Late Filing Penalty (IRC §6699)

If your S-corporation files Form 1120-S late and the delay is not due to reasonable cause, the IRS charges a per-shareholder, per-month penalty under Internal Revenue Code §6699.

For 2024 tax year returns required to be filed in 2025, the Form 1120-S instructions provide that:

  • The penalty is $245 per shareholder per month or part of a month,
  • Capped at 12 months,
  • Based on the number of persons who were shareholders during any part of the tax year.

Important: This dollar amount is indexed periodically for inflation. Always check the latest Form 1120-S instructions for the current rate.

Example (Federal)
Your S-corp has 3 shareholders and files its 1120-S 4 months late.

  • Penalty ≈ $245 × 3 shareholders × 4 months = $2,940,
  • Even if the S-corp itself doesn’t owe any corporate-level tax.

This per-shareholder penalty can apply whether or not there is tax due. If tax is due, additional percentage-based penalties can stack on top.

B. Additional Failure-to-File and Failure-to-Pay Penalties (If Tax Is Owed)

If your S-corporation has corporate-level tax due (for example, built-in gains tax), additional penalties may apply:

  • Failure-to-file (general): Typically 5% of the unpaid tax per month or part of a month, up to 25% of the unpaid tax.
  • Failure-to-pay: Generally 0.5% of the unpaid tax per month or part of a month, up to 25%.

These amounts are in addition to the per-shareholder penalty under IRC §6699 when there is tax due.

C. Interest on Unpaid Tax and Penalties

On top of penalties, the IRS charges interest on:

  • Any unpaid tax, and
  • Certain penalties

Interest compounds daily at a rate the IRS sets quarterly and continues until the balance is paid in full.

3. Arizona S Corporation Late Filing Penalties (Form 120S)

If your S-corporation is doing business in Arizona, you must also deal with Arizona Department of Revenue (ADOR) penalties for late or underpaid Form 120S and related taxes.

A. Late Filing Penalty (Arizona)

Arizona imposes a late filing penalty when returns are filed after the original or extended due date:

  • The late filing penalty is generally 4.5% of the tax required to be shown on the return per month or fraction of a month,
  • Up to a maximum of 25% of the tax required to be shown.

This penalty is based on the amount of tax due with the return, not per shareholder.

B. Late Payment Penalty

If your S-corp owes Arizona tax and doesn’t pay on time:

  • The late payment penalty is generally 0.5% of the unpaid tax per month or fraction of a month,
  • Often capped at around 10% of the unpaid tax.

Arizona generally limits the combined late filing and late payment penalties to no more than 25% of the unpaid tax.

C. Extension Underpayment Penalty

If you file an extension but don’t pay enough with that extension, Arizona may assess an extension underpayment penalty:

  • Typically 0.5% of the unpaid tax for each 30-day period or fraction thereof between the original due date and the date the tax is paid,
  • Up to a maximum of 25% of the underpayment.

Taxpayers subject to the extension underpayment penalty are typically not also charged the separate late payment penalty on the same underpaid amount.

D. Interest on Unpaid Arizona Tax

Arizona also charges interest on unpaid tax and certain penalties:

  • Interest accrues from the original due date until the tax is paid,
  • At a rate set periodically under Arizona law.

Interest is in addition to any late filing, late payment, or extension underpayment penalties.

E. Arizona PTE Election and Late Payments

For taxable years beginning after December 31, 2021, S-corporations can elect into the Arizona Pass-Through Entity (PTE) tax, which:

  • Imposes an entity-level tax (currently 2.5%) on certain Arizona-source income for participating owners, and
  • Is intended to provide a workaround to the federal SALT cap for those owners.

If your S-corp elects into the Arizona PTE tax and:

  • Files the PTE return late, or
  • Underpays the PTE tax,

then the same general penalty and interest framework (late filing, late payment, extension underpayment, and interest) can apply to those PTE amounts.

4. Late S Election vs. Late S-Corp Tax Return

Many owners confuse a late S-election with a late S-corporation tax return.

Late S-Election (Form 2553)

If your S-election (Form 2553) wasn’t filed on time, the IRS may treat your entity as:

  • A C-corporation, or
  • A partnership or disregarded entity (depending on the structure)

This can lead to:

  • Unexpected double taxation if treated as a C-corp
  • A mismatch between how owners have been taking distributions and how the IRS views the entity
  • Potential need to rework earlier-year filings

The IRS has procedures to request relief for a late S-election if:

  • You intended to be an S-corp,
  • You met the eligibility rules, and
  • You missed the deadline due to oversight or misunderstanding.

These rules are described in the Form 2553 instructions and related revenue procedures.

Arizona generally conforms to federal S-corporation status — Arizona taxable income for S-corps typically starts with federal income and then makes Arizona-specific additions and subtractions. But you still must file Arizona Form 120S and handle any Arizona taxes (including any PTE election).

Late S-Corp Tax Return (1120-S / 120S)

Even if your S-election is valid and timely, filing:

  • Form 1120-S (federal), or
  • Form 120S (Arizona)

late can trigger the penalties described above.

So you can have:

  • A valid S-election and
  • Significant IRS and Arizona penalties for late returns and late payments.

They’re separate issues that both need attention.

5. Practical Consequences Beyond the Dollar Penalties

The penalties are painful — but the side effects of filing late can be just as frustrating.

Delayed K-1s to Shareholders

Shareholders can’t file accurate personal returns until they get their Schedule K-1s. Late K-1s often mean:

  • Late or amended federal 1040s and Arizona individual returns,
  • Extra preparation fees,
  • Frustration for owners and spouses.

Cash-Flow Strain

Penalties plus interest can turn a manageable balance into a cash-flow problem, especially for:

  • New S-corps or LLCs taxed as S-corps
  • Seasonal or cyclical businesses

Audit and Compliance Risk

A pattern of:

  • Late filing,
  • Non-filing, or
  • Unpaid balances

can attract attention from tax authorities — especially if combined with other issues like unfiled payroll returns, late Arizona TPT returns, or missing 1099s.

Banking and Financing Issues

Lenders frequently ask for the last 1–3 years of business and personal tax returns. Late returns can:

  • Delay approvals, or
  • Lead to outright denials of financing.

6. What To Do If Your S Corporation Is Already Late

If your S-corp (or LLC taxed as an S-corp) is already late with federal or Arizona filings, the most important step is to act quickly.

A. File and Pay As Soon As Possible

For both the IRS and Arizona:

  • Many penalties are calculated per month or part of a month the return or payment is late.
  • Being one day late can be treated the same as being 29 days late for that month’s penalty.

Even if you can’t pay the full amount:

  • File the returns as soon as possible to prevent or reduce failure-to-file penalties.
  • Pay as much as you can to reduce failure-to-pay and extension underpayment penalties and interest.

Every month you wait generally makes the problem more expensive.

B. Request IRS Penalty Relief (When Appropriate)

The IRS offers two common types of penalty relief:

First-Time Abatement (FTA)

For taxpayers with a clean recent compliance history, the IRS may waive certain penalties once for a given period.

Reasonable Cause Relief

If your failure to file or pay was due to reasonable cause and not willful neglect — such as:

  • Serious illness or death in the family
  • Natural disasters
  • Records destroyed by casualty
  • Reliance on incorrect professional advice

— you may qualify for penalty relief.

Requests usually require:

  • A detailed explanation of the facts,
  • Documentation where possible, and
  • Evidence that you corrected the problem once you became aware of it.

C. Request Arizona Penalty Relief

Arizona allows for some penalty relief as well:

  • ADOR may waive penalties based on reasonable cause — for example, serious illness, disasters, or other events beyond the taxpayer’s control, supported by documentation.

While Arizona does not have a general “first-time abatement” program identical to the IRS, a solid reasonable cause narrative — especially coupled with documented IRS abatement for the same year — can sometimes support penalty relief at the Arizona level.

D. Clean Up Multiple Years at Once

If you’re behind on several years:

  1. Start with the oldest year and move forward in order.
  2. Make sure shareholder basis, distributions, and any Arizona PTE elections are handled correctly.
  3. Build a cash-flow plan so you can catch up federal and Arizona balances over time without crippling operations.
  4. Consider installment agreements with the IRS and/or Arizona if balances are significant.

7. How a CPA Can Help With Late S-Corp Filings (Arizona & Federal)

Because S-corporations involve:

  • Entity-level filings (Form 1120-S and Arizona Form 120S)
  • Shareholder-level reporting (Schedule K-1s and individual returns)
  • State-specific items like Arizona’s PTE election and unique penalty structure

…cleaning up late filings is rarely a simple DIY project.

A CPA who regularly works with S-corps and Arizona clients can:

  • Reconstruct books and records when information is incomplete
  • Prepare and file past-due 1120-S and 120S returns correctly
  • Analyze whether reasonable cause or IRS First-Time Abatement is realistic
  • Coordinate IRS and Arizona penalty relief requests
  • Set up a compliance calendar and systems so you don’t miss future deadlines

8. FAQs: Late S Corporation Filing (IRS & Arizona)

What happens if my S-corp return is just one day late?

For both the IRS and Arizona, many penalties are calculated per “month or part of a month” the return or payment is late. That means:

  • Being 1 day late can be treated the same as being 29 days late for that month’s penalty calculation.

Does filing an extension avoid late filing penalties?

A valid extension:

  • Extends the time to file,
  • Does not extend the time to pay.

If you:

  • File by the extended due date, you generally avoid failure-to-file penalties (including the IRC §6699 penalty at the federal level and Arizona’s late filing penalty on Form 120S).
  • Still owe tax as of the original due date, you may still face late-payment and/or extension underpayment penalties plus interest, both federally and in Arizona.

If my S-corp has no income, can I still get penalties?

Yes.

  • The IRS can impose the per-shareholder late filing penalty for a late 1120-S even if there is no tax due.
  • Arizona can impose late filing penalties on Form 120S when there is tax required to be shown on the return, and late payment or extension underpayment penalties if tax is unpaid by the due date.

The absence of income or tax does not automatically protect you from late-filing penalties.

How does the Arizona PTE tax affect late filing penalties?

If your S-corp makes the Arizona PTE election:

  • The PTE tax is an entity-level tax at a flat rate on qualifying income.
  • Late or underpaid PTE filings can trigger the same types of penalties and interest — late filing, late payment, and extension underpayment — on that PTE tax, in addition to any pass-through filing issues for shareholders.

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