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An S Corporation is not a type of business entity. It is a federal tax classification available to qualifying corporations and LLCs that elect to have their business income pass through to shareholders for tax purposes.
The S Corp designation is governed by Subchapter S of the Internal Revenue Code. When you elect S Corp status, the business itself generally does not pay federal income tax. Instead, income, losses, deductions, and credits flow through to shareholders, who report them on their personal returns. [13]
In Wisconsin, a federal S Corp is automatically treated as a tax-option (S) corporation and files Form 5S, Wisconsin Tax-Option (S) Corporation Franchise or Income Tax Return. By default, the S Corp itself does not pay Wisconsin entity-level income or franchise tax; shareholders pay Wisconsin individual income tax on their pro rata share of pass-through income at graduated rates of 3.50%, 4.40%, 5.30%, and 7.65%.[1] [6]
Wisconsin also offers an elective entity-level tax under Wis. Stat. sec. 71.365(4m)(a). When shareholders holding more than 50% of the shares consent, the S Corp may elect to pay Wisconsin tax at the entity level at a flat 7.9% rate, computed on Schedule 5S-ET. Income subject to the election is excluded from the shareholders Wisconsin adjusted gross income, which preserves the federal SALT deduction. [7] [14]
For business owners earning $60,000 or more in net business income, the S Corp election can provide meaningful self-employment tax savings. Only the salary you pay yourself as a W-2 employee is subject to Social Security and Medicare taxes; distributions beyond reasonable compensation are not.
| Action | Deadline | Notes |
|---|---|---|
| File IRS Form 2553 | Within 2 months and 15 days after the start of the tax year | For a January 1 tax year, the deadline is March 15. Late election relief may be available under IRS Rev. Proc. 2013-30. [3] |
| File Form 5S (Wisconsin) | March 15 (calendar-year filers) | 15th day of the 3rd month after the close of the tax year. Same deadline as the federal Form 1120-S. [9] |
| File Form 1120-S (Federal) | March 15 (calendar-year filers) | Distribute Schedule K-1s to shareholders. [3] |
| Wisconsin Form 5S extension | Automatic 7-month extension | Wisconsin grants an automatic 7-month extension for Form 5S. Check Item B on Form 5S to claim it. Payment of any balance due is still required by March 15 to avoid interest. [1] [9] |
| Elect Wisconsin entity-level tax (Schedule 5S-ET) | By the original or extended due date of Form 5S | Made by checking box #7 in Part A of Form 5S. Requires the consent of shareholders holding more than 50% of the shares. The election is annual and can be revoked by amended return. [1] [7] |
| Pay quarterly estimated tax | April 15, June 15, September 15, December 15 | Required if expected Wisconsin liability (entity-level tax or franchise tax) exceeds $500. Use Form Corp-ES. [9] |
| File Wisconsin Annual Report (WDFI) | End of the calendar quarter in which the entity was registered | Stock corporations and LLCs file with WDFI. $25 online or $40 by paper. [10] |
| Set up payroll | Before paying yourself a salary | Register with the Wisconsin Department of Workforce Development for unemployment insurance and with the Wisconsin Department of Revenue for withholding before issuing W-2 wages. [11] [12] |
An S Corp is a tax classification, not a standalone entity. You must have an active Wisconsin corporation or LLC on file with the Wisconsin Department of Financial Institutions before you can elect S Corp tax treatment with the IRS.
If you want to form an LLC first, check this guide.
If you want to incorporate as a C Corp first, check this guide.
Already have an existing LLC or corporation? Move to Step 1.
Form 2553, Election by a Small Business Corporation, is the IRS form that officially elects S Corp tax treatment at the federal level. It must be filed no later than 2 months and 15 days after the beginning of the tax year the election is to take effect. For a calendar-year corporation electing S Corp status for 2026, the deadline is March 15, 2026. [3]
Form 2553 collects the following information:
All shareholders must sign the consent portion of the form before submission. An unsigned form will be rejected by the IRS.
You can submit Form 2553 by mail or fax. There is no filing fee.
If your principal business office is located in Wisconsin, mail Form 2553 to: Department of the Treasury, Internal Revenue Service, Kansas City, MO 64999. [8]
Fax number for Wisconsin businesses: 855-887-7734. [8]
Faxing is typically faster than mailing. Keep your fax confirmation receipt. The IRS will issue a CP261 acceptance notice to confirm your S Corporation election.
Wisconsin follows the federal S Corp classification automatically under Wis. Stat. sec. 71.365(4)(a). Once your federal Form 2553 is accepted, Wisconsin will treat your business as a tax-option (S) corporation when you file Form 5S. There is no separate Wisconsin election form to submit for federal S status. [16] [1]
After your federal acceptance, retain a copy of your IRS CP261 acceptance letter with your tax records and use it to support your first Form 5S filing.
As an S Corp shareholder-employee, you are required to pay yourself a reasonable salary through W-2 payroll. The IRS scrutinizes S Corps that pay unreasonably low salaries to avoid payroll taxes.
The IRS expects your salary to reflect what someone performing similar work, in the same industry and the same region, would typically earn. There is no fixed formula, but the IRS flags S Corps where compensation is well below market and most of the owner pay comes through distributions.
Setting your salary too low risks the IRS reclassifying distributions as wages, making them subject to payroll taxes plus penalties and interest.
If you do not already have an EIN, apply at no charge on the IRS website (irs.gov). An EIN is a nine-digit federal ID used for tax filings, hiring employees, and opening business accounts.
Note: After obtaining your EIN, open a dedicated business bank account to keep your personal and business finances separate. This is essential to maintain your limited liability protection.
Every Wisconsin business corporation and LLC must file an annual report with WDFI. The fee is $25 online or $40 by paper for both stock corporations and LLCs. The report is due by the end of the calendar quarter in which the entity was originally registered. Failure to file may lead to administrative dissolution. [10] [5]
File IRS Form 1120-S and distribute Schedule K-1s to all shareholders by March 15 (calendar-year filers). File Wisconsin Form 5S by the same March 15 deadline. If the S Corp has not made the entity-level tax election, no entity-level franchise or income tax is owed on the Wisconsin return. [9] [1]
Wisconsin grants an automatic 7-month extension for Form 5S; check Item B on Form 5S and enter the extended due date. Federal extensions automatically extend the Wisconsin due date to 30 days after the federal extended due date. Payment of any balance due is still required by March 15 to avoid interest. [1] [9]
If the S Corp expects to owe more than $500 in Wisconsin tax for the year (most commonly when the entity-level tax election is made), it must pay quarterly estimated tax on Form Corp-ES. [9]
Wisconsin charges interest at 12% per year on unpaid tax during the extension period and 18% per year on tax not paid by the unextended due date. Late-filing penalties apply if the return is not filed by the extended due date. Maintaining an active registered agent and on time filings protects your S Corp status. [9]
If you fail to file Form 2553 with the IRS on time, your S Corp election will not take effect for the current tax year. Your business will be taxed as a C Corporation (or as a sole proprietorship/partnership if the underlying entity is an LLC) for that year, costing you the self-employment tax savings until the next tax year.
The IRS offers late election relief under Revenue Procedure 2013-30. To qualify, you must file within 3 years and 75 days of the intended effective date, demonstrate reasonable cause for the late filing, and confirm that the entity has consistently filed as if the S election were in effect. [3]
Because Wisconsin follows the federal S election automatically, there is no separate state late-election process. Once the IRS grants late election relief, Wisconsin will treat the entity as a tax-option (S) corporation for the same tax year. [16] [1]
At the federal level, the S Corp election can be revoked by filing a statement of revocation with the IRS, signed by shareholders holding more than 50% of the outstanding shares. The revocation is effective the first day of the tax year if filed by the 15th day of the third month; later filings take effect the following tax year. [3]
Because Wisconsin follows the federal classification, a federal revocation automatically terminates the Wisconsin tax-option (S) corporation status. The entity then files Form 4 (Wisconsin Corporation Franchise or Income Tax Return) as a C Corp for tax years beginning after the federal revocation. Once revoked, you generally cannot re-elect S Corp status for five years without IRS consent. [16] [1]
By default, a Wisconsin tax-option (S) corporation does not pay franchise or income tax at the entity level. Income, gain, loss, and deductions pass through to shareholders, who report their pro rata share on their Wisconsin individual returns at graduated rates of 3.50%, 4.40%, 5.30%, and 7.65%.[1] [6]
| Entity Type | Wisconsin Entity-Level Tax |
|---|---|
| S Corporation (default) | None at entity level; shareholders pay individual income tax at graduated rates up to 7.65% [1] [6] |
| S Corp with entity-level election | Flat 7.9% on Wisconsin net income under sec. 71.365(4m)(a); shareholders exclude that income [7] [14] |
| Partnership / LLC (partnership) | None at entity level by default; partnership-level election available under sec. 71.21(6) [1] |
| C Corporation | Flat 7.9% corporate franchise tax under sec. 71.27 [15] |
| Sole prop / disregarded LLC | No entity-level tax; owner pays Wisconsin individual income tax at graduated rates [6] |
Under Wis. Stat. sec. 71.365(4m)(a), a tax-option (S) corporation may elect to pay Wisconsin tax at the entity level. Shareholders holding more than 50% of the shares must consent. The election is made annually by checking box #7 in Part A of Form 5S and is computed on Schedule 5S-ET, Entity-Level Tax Computation. Income subject to the election is excluded from each shareholder Wisconsin adjusted gross income, preserving the federal SALT deduction.[1] [7] [14]
Note: the elective rate is a flat 7.9%, which is higher than the top Wisconsin individual rate of 7.65%. That makes the math here more nuanced than the typical SALT-cap workaround. The election is best for shareholders whose marginal rate is at or near the top bracket and whose federal tax benefit from preserving the SALT deduction is greater than the 0.25 percentage-point Wisconsin rate gap. Shareholders in lower brackets (3.50%, 4.40%, or 5.30%) generally pay more total state tax under the election than they would in the default pass-through regime, so the decision should be modeled with a CPA. [6] [7]
The election may be revoked by filing an amended Form 5S on or before the extended due date, with consent from shareholders holding more than 50% of the shares. [1]
When the entity-level election is not made, Wisconsin imposes individual income tax on each shareholder pro rata share of S Corp pass-through income at graduated 2025 rates of 3.50%, 4.40%, 5.30%, and 7.65%. Nonresident shareholders pay tax only on the share attributable to Wisconsin sources. [6]
Wisconsin state sales and use tax is 5% on the sales price of taxable goods and services. 70 counties impose an additional 0.5% county tax (Milwaukee County is 0.9%), and the City of Milwaukee imposes a 2% city sales tax. Register through My Tax Account at revenue.wi.gov. [6]
| Item | Cost |
|---|---|
| Articles of Incorporation (domestic stock corporation, WDFI) | $100 paper or $100 online [10] |
| Articles of Organization (domestic LLC, WDFI) | $170 paper or $130 online [10] |
| IRS Form 2553 filing | No fee [3] |
| Federal EIN (Form SS-4) | No fee |
| Annual Report (stock corporation or LLC, WDFI) | $25 online or $40 paper [10] |
| Expedited processing (next business day, WDFI) | $100 [10] |
| Registered Agent service (typical commercial) | $100 to $300 per year |
| Feature | S Corporation | LLC |
|---|---|---|
| Formation Document | Articles of Incorporation ($100) | Articles of Organization ($130 online / $170 paper) |
| Federal Tax Treatment | Pass-through (Form 1120-S) | Pass-through by default (Form 1065 or Schedule C) |
| Wisconsin Tax Treatment | Form 5S; no entity-level tax unless elected | Form 3 (partnership) or no return (disregarded) |
| Annual Report | $25 online / $40 paper | $25 online / $40 paper |
| Self-Employment Tax | Only on W-2 salary | 15.3% on all net earnings |
| Ownership Limits | Max 100 U.S.-person shareholders, one class of stock | Unlimited members, any type |
| Management | Directors and officers required | Flexible; member or manager managed |
| Reasonable Salary Required | Yes | No |
| Entity-Level Tax Election | Yes (flat 7.9% under sec. 71.365(4m)) | Yes if taxed as S Corp or partnership |
| Annual Reporting Deadline | End of registration quarter | End of registration quarter |
| Best For | Owners earning $60K+ wanting SE-tax savings | Small businesses prioritizing simplicity |
The S Corp election makes the most financial sense when your net business income is high enough that the self-employment tax savings outweigh the cost of running payroll and the additional compliance burden. Use this guide:
| Net Business Income | Recommendation |
|---|---|
| Under $40,000 | An S Corp likely does not make sense. Payroll and compliance costs typically erase the savings. |
| $40,000 to $60,000 | Borderline. Run the numbers with a CPA. Savings may be modest after payroll-service fees. |
| $60,000 to $100,000 | S Corp election usually save $2,000 to $5,000 per year in self-employment taxes. |
| $100,000 to $200,000 | Strong candidate. Savings often $5,000 to $10,000+ per year. |
| Over $200,000 | Almost always advantageous unless you have specific reasons (foreign investors, IPO plans) to remain a C Corp or LLC. |
Keep in mind that Wisconsin annual report fees, registered agent service, payroll setup, and ongoing CPA fees together typically add $800 to $2,500 in annual costs. S Corps also have ownership restrictions that may not suit every business model, and shareholders in lower Wisconsin tax brackets may find the default pass-through regime preferable to the 7.9% entity-level election.
| Requirement | Details |
|---|---|
| Form 1120-S (Federal) | Due March 15. Reports S Corp income. Distribute K-1s to shareholders. |
| Form 5S (Wisconsin) | Due March 15. Reports Wisconsin items, applies the entity-level election if made, and issues Schedule 5K-1 to shareholders. [9] |
| Annual Report (WDFI) | Filed with the Wisconsin Department of Financial Institutions by the end of the calendar quarter in which the entity was registered. $25 online or $40 paper. [10] |
| Form 941 (Federal Payroll Tax) | Filed quarterly. Reports federal income tax, Social Security, and Medicare withheld. |
| Form WT-6 / WT-7 (Wisconsin Withholding) | Wisconsin employer withholding deposits and annual reconciliation filed with the Wisconsin Department of Revenue. [12] |
| UCT-101 (DWD quarterly contribution and wage report) | Quarterly UI contribution and wage report filed with the Wisconsin Department of Workforce Development. [11] |
| W-2s and 1099s | Distributed by January 31. Filed with IRS, Social Security Administration, and Wisconsin Department of Revenue. |
| Estimated Tax Payments | Quarterly federal and Wisconsin estimated tax if expected liability exceeds applicable thresholds. |
| Entity-Level Tax Election (if applicable) | Made annually by checking box #7 in Part A of Form 5S. Requires consent of more than 50% of shares. [1] [7] |
| Registered Agent Maintenance | Keep agent and Wisconsin street address current with WDFI under Wis. Stat. sec. 180.0501. [4] |
Bibliography
[1] Wisconsin Department of Revenue. Tax-Option (S) Corporation General Election Questions. Accessed May 18, 2026.
[2] Wisconsin Department of Revenue. Tax-Option (S) Corporation Determining Income and Computing Tax. Accessed May 18, 2026.
[3] IRS. Instructions for Form 2553. Accessed May 18, 2026.
[4] Wisconsin Legislature. Wis. Stat. sec. 180.0501 (Registered Office and Registered Agent). Accessed May 18, 2026.
[5] Wisconsin Department of Financial Institutions. Annual Report Instructions (Form CORP5i). Accessed May 18, 2026.
[6] Wisconsin Department of Revenue. Tax Rates (Individual, Sales, and Business). Accessed May 18, 2026.
[7] Wisconsin Legislature. Wis. Stat. sec. 71.365(4m)(a) (Tax-Option (S) Corporation Entity-Level Tax). Accessed May 18, 2026.
[8] IRS. Where to File Your Taxes (for Form 2553). Accessed May 18, 2026.
[9] Wisconsin Department of Revenue. 2025 Form 5S Instructions (IC-154). Accessed May 18, 2026.
[10] Wisconsin Department of Financial Institutions. DFI Corporation Fees. Accessed May 18, 2026.
[11] Wisconsin Department of Workforce Development. Employer UI Registration. Accessed May 18, 2026.
[12] Wisconsin Department of Revenue. Wisconsin Withholding Tax. Accessed May 18, 2026.
[13] IRS. S Corporations. Accessed May 18, 2026.
[14] Wisconsin Department of Revenue. 2025 Schedule 5S-ET Instructions (IC-110). Accessed May 18, 2026.
[15] Wisconsin Legislature. Wis. Stat. sec. 71.27 (Rates of Taxation). Accessed May 18, 2026.
[16] Wisconsin Legislature. Wis. Stat. sec. 71.365(4)(a) (Tax-Option Corporation Definition). Accessed May 18, 2026.
Official Resources
