File as soon as you can. This is fixable, and you may qualify to have the penalty waived. The amount depends on the tax year, whether you filed an extension, and when you file the return.

1. Check your filing deadline. A calendar-year S corporation generally must file 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 get 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. You can use TurboTax Business or its S-corporation service for the tax year you’re filing. Regular personal TurboTax/Home & Business does not prepare an 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 who works 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 a corporation with 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, a return due in 2026 that is four months or partial months late carries a $1,020 penalty 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. Request 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 a serious illness or a death in the immediate family. Keep documentation of what happened, when it happened, and how it prevented you from filing. If you receive a penalty notice, call the number on it to 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))

Check your personal return, state return, and payroll filings too. Each has separate requirements and possible penalties.

Which tax year are you filing, which state is the business in, and did you or an accountant submit Form 7004? Those details, along with your planned filing date, will help calculate the likely penalty more precisely.