**File as soon as you can—this is fixable, and you may qualify to have the penalty waived.** The exact amount depends on the tax year, whether an extension was filed, and your filing date.

1. **Check whether you’re actually late.** A calendar-year S corporation generally files **Form 1120-S by March 15**, adjusted for weekends and holidays. A timely Form 7004 extension generally gives you until September 15. For example, the 2025 return was due March 16, 2026. You generally can’t obtain an extension retroactively after the deadline. ([IRS tax calendar](https://www.irs.gov/publications/p509), [extension instructions](https://www.irs.gov/instructions/i7004))

2. **Prepare the corporate return and your Schedule K-1.** Yes, you can use **TurboTax Business or its S-corporation service**, using the correct tax-year product. Regular personal TurboTax/Home & Business does not prepare the S corporation’s return. Your K-1 then goes into your separate personal return. If your books, payroll, or shareholder distributions need sorting out, I’d use a CPA or enrolled agent experienced with S corporations. ([TurboTax filing guidance](https://ttlc.intuit.com/turbotax-support/en-us/help-article/form-1120/form-1120-u-return-corporation/L1yul3DjM_US_en_US))

3. **Expect a monthly federal filing penalty, even if the corporation owes no income tax.** For one shareholder, the base penalty is:

   | Return originally due in | Each month or partial month late | Maximum, 12 months |
   |---|---:|---:|
   | 2026 | $255 | $3,060 |
   | 2025 | $245 | $2,940 |
   | 2024 | $235 | $2,820 |

   For example, **four months or partial months late on a return due in 2026 means $1,020**, before relief. These amounts assume no corporate-level tax is due; additional penalties can apply if it is. ([IRS penalty rules](https://www.irs.gov/payments/failure-to-file-penalty))

4. **Seek penalty relief.** A good compliance history may qualify you for first-time relief; the IRS also says automatic relief begins in summer 2026 for qualifying returns. Your personal issues could support **reasonable-cause relief**, particularly serious illness or a death in the immediate family. Keep documentation showing what happened, the dates, and how it prevented filing. If you receive a penalty notice, call the number on it and request relief. Approval depends on your circumstances. ([IRS administrative relief](https://www.irs.gov/payments/administrative-penalty-relief), [reasonable-cause relief](https://www.irs.gov/payments/penalty-relief-for-reasonable-cause))

Also check your **personal return, state return, and payroll filings**—they have separate obligations and possible penalties.

**Which tax year are you filing, which state is the business in, and did you or an accountant submit Form 7004?** With those details and your planned filing date, the likely penalty can be calculated more precisely.