How much does it cost to start a sole proprietorship in South Dakota?

Nothing at the state level. The only common state cost is the $10 fictitious business name registration with the Secretary of State, if you use a trade name. A sales tax license, occupational licenses, and any local city business license are separate and depend on what you do.

What is a fictitious business name in South Dakota?

It is South Dakota's version of a DBA. Under SDCL chapter 37-11, a person regularly conducting business must file a fictitious name statement unless the business name plainly shows the true surname of each person interested in the business. The registration fee is $10.

Do I need an EIN as a South Dakota sole proprietor?

Not necessarily. A sole proprietor with no employees may use a Social Security number. You need an EIN if you hire employees, owe certain excise taxes, or set up a solo 401(k). An EIN is free from the IRS and keeps your Social Security number off vendor and client paperwork.

Sole Proprietorship in South Dakota (2026)

Q: Do I have to register a sole proprietorship in South Dakota?

No. South Dakota requires no state formation filing to operate as a sole proprietor, and there is no formation fee. You only file if you trade under a name other than your own legal name, which requires a fictitious business name registration, or if your activity requires a sales tax license or an occupational license.

Q: Does South Dakota have an income tax on business profit?

No. South Dakota has neither a personal income tax nor a corporate income tax, so a sole proprietor files no state income tax return on business profit. Federal tax still applies through Schedule C and self-employment tax on Schedule SE.

Q: Should I switch from a sole proprietorship to an LLC?

Switch when your liability exposure grows - leases, employees, inventory, or contracts with real damages. South Dakota LLC Articles of Organization are $150 online or $165 on paper, and the annual report is $55 online. A single-member LLC still files Schedule C, so the tax filing barely changes.

Fact-checked by the LegalGlass editorial team against primary sources · Published Aug 20, 2026 · Last updated Aug 20, 2026

A sole proprietorship is the default form of business in South Dakota: if you start working for yourself and file nothing, you already have one. There is no state formation filing and no formation fee. A fictitious business name registration costs $10, a sales tax license comes from the Department of Revenue, and South Dakota levies no personal income tax.

Quick Answer

Formation filing: None - no state entity filing is required
Cost to start: $0 at the state level
Fictitious business name: $10 to register with the Secretary of State (SDCL ch. 37-11)
Federal tax: Schedule C with Form 1040; self-employment tax on Schedule SE
State income tax: None - South Dakota has no personal or corporate income tax
Liability: Unlimited personal liability for business debts

What a Sole Proprietorship Is in South Dakota

A sole proprietorship is an unincorporated business owned by one person. It is not a separate legal entity: the owner and the business are the same person in the eyes of the law. That is why there is nothing to file to create one. The moment you sell a service or a product for profit in South Dakota, you are operating as a sole proprietor by default.

Because there is no separate entity, there is also no liability separation. Business debts are personal debts, and a judgment against the business reaches your personal bank account, vehicle, and other assets. That single fact is the reason most owners eventually move to an LLC; see what an LLC is for the comparison.

What You Do Not Have to File

South Dakota requires no articles, no certificate, and no registered agent for a sole proprietorship. The Secretary of State's business register is for entities - LLCs, corporations, partnerships - and a sole proprietor simply is not on it unless a fictitious name is registered.

That means the true state cost of starting is $0. Any cost you incur comes from the optional or activity-specific items below: a business name registration, a sales tax license, a professional or occupational license, and local municipal requirements. Do not pay a service to "register your sole proprietorship" in South Dakota; there is no such registration.

Registering a Fictitious Business Name ($10)

You may operate under your own legal name with no filing at all. If you want to trade under a different name - "Black Hills Signworks" instead of "Jane Doe" - South Dakota requires a fictitious business name registration. Under SDCL chapter 37-11, a person regularly conducting business in the state must file a fictitious name statement unless the name plainly shows the true surname of each person interested in the business, or the name is already on file in a required business filing.

The fee is $10 for the initial registration, and the same $10 applies to an amendment or renewal, per the Secretary of State's filing fee schedule. Banks generally require the registration before opening an account in the trade name. Registering the name does not give you trademark rights - see the national trademark guide.

Sales Tax and the Department of Revenue

South Dakota has a broad sales and use tax that reaches many services as well as goods. If you sell taxable products or services, you register for a sales tax license with the South Dakota Department of Revenue before you begin making taxable sales, then collect and remit on the schedule the department assigns.

Two points catch new proprietors. First, South Dakota taxes many services that other states exempt, so do not assume a service business is outside the system - check the department's guidance for your industry. Second, contractors and certain trades have their own excise tax regime rather than ordinary sales tax. Register before your first sale; back taxes and penalties accrue from the first taxable transaction, not from the date you eventually register.

Federal Taxes: Schedule C and Schedule SE

A sole proprietor reports business income and expenses on Schedule C, filed with Form 1040. Net profit flows to the owner's individual return and is also carried to Schedule SE, where self-employment tax of 15.3% is computed - 12.4% Social Security plus 2.9% Medicare - on 92.35% of profit, once net earnings reach $400 for the year.

Nobody withholds from a proprietor's profit, so the IRS collects through quarterly estimates on Form 1040-ES. See self-employment tax in South Dakota and the self-employment tax calculator. An EIN is optional for a proprietor with no employees, who may use a Social Security number, but it is free and keeps that number off vendor forms.

No South Dakota Income Tax

South Dakota imposes no personal income tax and no corporate income tax. A sole proprietor files no state income tax return on business profit. That is a genuine and unusual advantage: in most states the same profit is taxed twice over, federally and by the state.

The state raises revenue instead through the sales and use tax, the contractors' excise tax, property tax at the local level, and industry-specific taxes such as those on banks and insurers. Plan for those rather than for an income tax bill. It also means the federal Schedule C is the only income tax return most South Dakota proprietors ever file.

Local Licenses and Industry Permits

The absence of a state formation filing does not mean no licensing. Many South Dakota municipalities require a local business license, and some require zoning approval for a home-based business. Regulated occupations - contractors, cosmetologists, health professionals, food service, alcohol - are licensed by their own boards or by the city.

Check three levels before you open: the state board for your occupation, the Department of Revenue for tax licensing, and your city or county for a general business license and zoning. See South Dakota business license requirements and how to start a business in South Dakota.

When to Convert to an LLC

The usual trigger is risk, not revenue. Once you sign leases, hire staff, carry inventory, take on physical-injury exposure, or sign contracts with real damages clauses, unlimited personal liability stops being an acceptable trade for saving a filing fee.

South Dakota's filing costs are modest. According to the Secretary of State's fee schedule, Articles of Organization for an LLC are $150 filed electronically or $165 on paper, and the LLC annual report is $55 online or $70 on paper. Against that, the liability separation is usually cheap insurance.

Converting is straightforward: form the LLC, move contracts, bank accounts, licenses, and insurance into the company's name, and stop signing personally. Tax treatment barely changes - a single-member LLC is a disregarded entity, so you keep filing Schedule C. See how to form an LLC in South Dakota and South Dakota Articles of Organization.

Frequently Asked Questions

Do I have to register a sole proprietorship in South Dakota?

No. There is no state formation filing. You file only for a trade name, a sales tax license, or an occupational license.

How much does it cost to start?

$0 at the state level. The common extra is the $10 fictitious business name registration.

Does South Dakota tax business profit?

No. There is no personal or corporate income tax. Federal Schedule C and Schedule SE still apply.

What is a fictitious business name?

South Dakota's DBA, required under SDCL ch. 37-11 unless the name shows the owner's true surname. The fee is $10.

Do I need an EIN?

Only with employees, certain excise taxes, or a solo 401(k) - but it is free and keeps your SSN off vendor forms.

When should I switch to an LLC?

When liability exposure grows. LLC Articles of Organization are $150 online or $165 on paper; the annual report is $55 online.

Sources

South Dakota Secretary of State - Filing fees ($10 fictitious business name; $150/$165 LLC Articles of Organization; $55/$70 annual report).
South Dakota Legislature - SDCL chapter 37-11 (fictitious business names).
South Dakota Legislature - SDCL chapter 47-34A (South Dakota Limited Liability Company Act).
South Dakota Department of Revenue - Businesses (sales tax license; contractors excise tax).
South Dakota Secretary of State - Business services.
IRS - Sole proprietorships.
IRS - About Schedule C (Form 1040).
IRS - Self-employment tax (15.3%; $400 threshold).
IRS - Get an Employer Identification Number.
IRS - About Form 1040-ES.

LegalGlass provides general information for educational purposes and is not legal advice, is not a law firm, and is not a substitute for advice from a licensed attorney or tax professional. Laws, fees, and thresholds change; verify current amounts with the South Dakota Secretary of State and the South Dakota Department of Revenue before acting.