How to Start an S Corp in Missouri (and When an LLC Should Elect)

An S Corporation, or S Corp, is a tax designation rather than a business structure. In Missouri, you form a corporation first, then elect S Corp taxation with the IRS. For existing LLCs, you can make the same election without restructuring. This guide covers formation from scratch, tax elections, and the specific advantages for Missouri business owners.

What You Need Before You Start

Gather these materials before filing:

• Desired business name, Check availability at https://bsd.sos.mo.gov/BusinessEntity/BESearch.aspx?SearchType=0
• Registered agent information, A Missouri resident or authorized business with a physical street address in Missouri
• Articles of Incorporation, Missouri Form Corp. 41 (for a new corporation)
• Shareholder information, Names, addresses, and ownership percentages of all shareholders
• Employer Identification Number (EIN), Applied for via IRS Form SS-4 (free online or by mail)
• IRS Form 2553, To elect S Corp taxation (filed separately with the IRS, generally no more than 2 months and 15 days after the start of the tax year the election is to take effect)
• Filing fee, $58 minimum for Articles of Incorporation (the fee rises with authorized shares above 30,000 shares or $30,000 par value)

Step 1: Choose Your Name and Verify Availability

Your corporation name must include "Corporation," "Incorporated," "Company," or an abbreviation like "Corp," "Inc," or "Co." It must be distinguishable from all other registered Missouri business entities on file with the Secretary of State.

Search the Secretary of State's business database at https://bsd.sos.mo.gov/BusinessEntity/BESearch.aspx?SearchType=0. If your preferred name is taken, modify it slightly and search again. Optionally, reserve the name for 60 days (renewable for two additional 60-day periods, up to 180 days total) by filing an Application for Reservation of Name (Form BE 1) for a $25 fee. This gives you breathing room while you prepare other documents.

Step 2: Appoint a Registered Agent

Missouri law requires every corporation to maintain a registered agent with a physical street address in Missouri. The registered agent may be:

• An individual resident of Missouri whose business office is identical to the registered office
• A corporation authorized to transact business in Missouri

A PO Box is not sufficient as a standalone address; you must provide a physical street address. Many business owners serve as their own registered agent. If you hire a registered agent service, confirm they maintain a physical office in Missouri and that the address is identical to your corporate registered office. Changes to your registered agent or office cost $10 to file with the Secretary of State.

Step 3: Prepare Articles of Incorporation

Use Missouri Form Corp. 41 (Articles of Incorporation of a For Profit Corporation). The form requires:

• Corporate name
• Registered agent name and address
• Street address of your registered office (must match the agent's office)
• Names and addresses of incorporators (usually the initial shareholders or their attorney)
• Number of authorized shares (Article Three must be completed, and the share count sets the filing fee)
• Optional: purpose clause or other provisions

You do not need to list shareholders in the Articles, nor do you need to specify the initial capital contribution. Keep the Articles simple; complex provisions belong in corporate bylaws (filed separately, not with the state).

Step 4: File Articles of Incorporation Online

File online through the Missouri Business Filings portal at https://bsd.sos.mo.gov/. Online filings are processed immediately in most cases. The filing fee is $58.

Alternatively, mail the Articles to:

Missouri Secretary of State
Corporations Division
PO Box 778
Jefferson City, MO 65102

Paper filings take longer; the Secretary of State does not publish a guaranteed turnaround time. Once filed, the Secretary of State issues a Certificate of Incorporation confirming your corporation's existence.

Step 5: Obtain Your Employer Identification Number (EIN)

Apply for an EIN from the IRS using Form SS-4. This is free and takes minutes online at irs.gov. You need an EIN before making an S Corp election, before opening a business bank account, and before hiring employees. The IRS issues your EIN immediately upon approval.

Step 6: Make Your S Corporation Election

File IRS Form 2553 (Election by a Small Business Corporation) to elect S Corp taxation. Timing matters:

• For a new corporation in its first year: File Form 2553 no more than 2 months and 15 days after the first day of the corporation's first tax year (which begins when it has shareholders, acquires assets or begins business). The election then takes effect for that first tax year.
• For an existing corporation in a later tax year: File Form 2553 during the preceding tax year or no more than 2 months and 15 days after the start of the tax year it is to take effect. Late elections may qualify for relief under IRS Rev. Proc. 2013-30.
• For an existing LLC: An LLC already taxed as a partnership or as a sole proprietorship can elect S Corp taxation using the same Form 2553. The LLC does not need to convert to a corporation; the election is purely a tax designation.

File Form 2553 with the IRS at the address shown on the form. Retain a copy for your records. The election stays in effect until it terminates or is revoked with the consent of shareholders holding more than half of the shares.

Step 7: Register for Missouri Taxes

Register with the Missouri Department of Revenue at https://dor.mo.gov/register-business/ if you have employees or owe Missouri income tax. Depending on your business, you may need to register for:

• Corporate income tax: S Corps pass income to shareholders, but the entity still files a Missouri S corporation return (Form MO-1120S). Missouri imposes a 4% flat corporate income tax on C Corps; S Corps are taxed as pass-through entities by Missouri (shareholders pay Missouri personal income tax at graduated rates, topping out at 4.70% in 2026).
• Sales tax: If you sell tangible goods or taxable services, apply for a sales tax license. Missouri's state sales tax is 4.225%.
• Payroll withholding: If you have employees, register for employer withholding with the Department of Revenue.
• Unemployment tax: Register with the Missouri Division of Employment Security.

Missouri has no statewide general business license or franchise tax (eliminated in 2016). Some cities require local business licenses; check with your city or county.

When Should an LLC Elect S Corp Taxation?

An LLC taxed as a sole proprietorship or partnership pays self-employment tax (Social Security and Medicare) on all profits. An S Corp election changes this: the owner becomes an employee, pays payroll tax only on wages, and receives the remaining profits as distributions (which avoid self-employment tax).

S Corp taxation typically makes sense if:

• Your net business income exceeds $60,000 to $80,000 per year (savings increase with higher income)
• You can justify a reasonable W-2 salary to yourself (the IRS scrutinizes unreasonably low salaries)
• You are comfortable with additional tax filing and payroll compliance

Savings are modest for lower incomes and offset by accounting and payroll costs.

Missouri-Specific Tax Advantages and Limitations

No franchise tax: Missouri eliminated its corporate franchise tax effective January 1, 2016. S Corps and traditional corporations owe no annual recurring tax to Missouri based on their structure.

No annual report for LLCs: Missouri LLCs file no annual or biennial report with the Secretary of State and owe no recurring maintenance fees. This is a key advantage over corporations.

S Corps must file annual reports: If you form a traditional corporation, it must file an Annual Registration Report with the Secretary of State each year. The fee is $20 online ($45 on paper), due at the end of the month in which the corporation was incorporated (for corporations formed on or after July 1, 2003). Late filings incur an additional $15 for each 30-day period.

Pass-through entity election: Missouri offers an optional pass-through entity (PTE) election that allows the entity (not the individual) to pay Missouri income tax on pass-through income, with shareholders claiming a credit on their personal returns. Its main purpose is to let owners work around the federal cap on deducting state and local taxes. Consult a CPA about whether this applies to your situation.

Tips and Common Mistakes to Avoid

Tip: Use your registered agent's address consistently. Always list the registered agent's address as your registered office address. Mismatches can cause the Secretary of State to flag your filing or, in extreme cases, lead to administrative dissolution if you later fail to maintain an agent.

Mistake: Forgetting the S Corp election. Filing a corporation and obtaining an EIN does not automatically make it an S Corp. You must file Form 2553 with the IRS. Without this, your corporation is taxed as a C Corp (4% flat tax on all profits in Missouri, no pass-through benefit).

Tip: Separate personal and business finances from day one. Open a dedicated business bank account immediately. Commingling funds weakens liability protection and creates accounting headaches when filing taxes.

Mistake: Paying yourself no salary as an S Corp. If your S Corp has profits, the IRS expects you to pay yourself a "reasonable salary" as an employee. Paying yourself only dividends or distributions and claiming zero wages is a red flag for an audit. The IRS's definition of reasonable is flexible and depends on your industry and role, but it generally means what similar businesses pay for similar work.

Tip: Keep detailed records of shareholder agreements and capital contributions. Document who owns what percentage and how much each shareholder invested. This is vital for tax purposes and protects you if disputes arise later.

Mistake: Assuming S Corp status is permanent. S Corp elections can terminate automatically if the business gains an ineligible shareholder (e.g., a non-resident alien or a corporation). Once terminated, you must reapply or request IRS relief.

Expected Results and Timeline

Once you file your Articles of Incorporation and receive your Certificate from the Missouri Secretary of State (typically within 1 business day for online filings), your corporation legally exists. After you file your Form 2553 S Corp election with the IRS and receive confirmation, your S Corp status becomes effective for the tax year shown on the election, as long as Form 2553 was filed on time.

Tax benefits from S Corp status appear on your first federal tax return. Missouri recognizes your S Corp status automatically once the IRS accepts your election; you do not file a separate Missouri election.

Legal and Tax Disclaimer

This article is informational only and does not constitute legal or tax advice. Formation requirements, tax treatment, and liability protections vary based on your specific business, ownership structure, and circumstances. Before forming a corporation or electing S Corp taxation, consult a qualified Missouri attorney and a certified public accountant (CPA). They can confirm that S Corp status makes sense for your business, ensure your filing is timely and compliant with IRS and Missouri requirements, and help you navigate ongoing compliance obligations.