State Comparison

South Dakota vs Illinois LLC

Side-by-side comparison of forming an LLC in South Dakota vs Illinois — fees, processing times, taxes, and decision factors to help you choose the right state for your business.

South Dakota

Filing fee$150

Processing5–10 days

Annual report$50

State income taxVaries by personal bracket

See state Secretary of State for specifics

Illinois

Filing fee$150

Processing5–10 days

Annual report$75

State income tax4.95% flat

1.5% replacement tax on S-corp net income

Lower state fees:

South Dakota — $200 total 1st-year state fees

Excludes franchise tax, registered agent, and other compliance costs

Pros and Cons

South Dakota (SD)

Pros

Established LLC statute
Pass-through taxation at federal level
No unusual restrictions on LLC ownership

Cons

Foreign qualification may be needed if operating elsewhere
Annual state compliance required to maintain good standing

Illinois (IL)

Pros

PTET election available to work around SALT cap
Strong Midwest economy centered on Chicago
Moderate state filing fees

Cons

1.5% replacement tax on S-corp net income
Annual report deadlines trigger loss of good standing if missed
Relatively high state income tax (4.95% flat)

Side-by-Side Comparison

Feature	South Dakota	Illinois
LLC filing fee	$150	$150
Corporation filing fee	$150	$150
Annual report fee	$50	$75
Processing time	5–10 days	5–10 days
State income tax	Varies by personal bracket	4.95% flat
Franchise / entity tax	See state Secretary of State for specifics	1.5% replacement tax on S-corp net income
Popular formation state?	No	No

Which Should You Choose?

Choose South Dakota if...

• Check state-specific requirements for your industry and structure

• You live or operate primarily in South Dakota — forming locally avoids foreign qualification costs and compliance in multiple states.

Choose Illinois if...

• PTET is a meaningful SALT-cap workaround for high earners

• Consider if operating in Chicago metro

• You live or operate primarily in Illinois — forming locally avoids foreign qualification costs and compliance in multiple states.

FAQ

Is it cheaper to form an LLC in South Dakota or Illinois?

South Dakota charges $150 filing + $50 annual report. Illinois charges $150 filing + $75 annual report. South Dakota is the cheaper option on state fees alone, though franchise tax and other compliance costs also matter.

Should I form my LLC in South Dakota or Illinois?

For most businesses, form in the state where you actually operate. South Dakota (Varies by personal bracket state income tax) and Illinois (4.95% flat state income tax) each have their specific characteristics. If you physically operate in one of these states, form there. Forming in South Dakota while operating in Illinois (or vice versa) means paying fees in both states.

Can I form my LLC in South Dakota and operate in Illinois?

Yes, but you'll need to "foreign qualify" in Illinois, which means paying a registration fee in Illinois plus ongoing compliance in both states. You'll also typically owe Illinois state taxes on income earned there regardless of where the LLC is formed. Forming in a single state (usually your home state) is typically cleaner and cheaper for small businesses.

What are the annual costs for an LLC in South Dakota vs Illinois?

South Dakota: See state Secretary of State for specifics — plus $100-$300/yr for a registered agent. Illinois: 1.5% replacement tax on S-corp net income — plus $100-$300/yr for a registered agent. Budget an additional $500-$2,000/yr for accounting, bookkeeping, and business license renewals regardless of state.

Which state has better asset protection — South Dakota or Illinois?

Asset protection varies by state statute. States like Wyoming, Nevada, and Delaware have the strongest charging-order-exclusive doctrines for LLC members. South Dakota and Illinois both offer LLC liability protection, but consult an attorney for state-specific asset protection planning if you have significant personal assets to shield.

South Dakota resources

Illinois resources

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Pros and Cons

South Dakota (SD)

Pros

Established LLC statute
Pass-through taxation at federal level
No unusual restrictions on LLC ownership

Cons

Foreign qualification may be needed if operating elsewhere
Annual state compliance required to maintain good standing

Illinois (IL)

Pros

PTET election available to work around SALT cap
Strong Midwest economy centered on Chicago
Moderate state filing fees

Cons

1.5% replacement tax on S-corp net income
Annual report deadlines trigger loss of good standing if missed
Relatively high state income tax (4.95% flat)

Side-by-Side Comparison

Feature	South Dakota	Illinois
LLC filing fee	$150	$150
Corporation filing fee	$150	$150
Annual report fee	$50	$75
Processing time	5–10 days	5–10 days
State income tax	Varies by personal bracket	4.95% flat
Franchise / entity tax	See state Secretary of State for specifics	1.5% replacement tax on S-corp net income
Popular formation state?	No	No

Which Should You Choose?

Choose South Dakota if...

• Check state-specific requirements for your industry and structure

• You live or operate primarily in South Dakota — forming locally avoids foreign qualification costs and compliance in multiple states.

Choose Illinois if...

• PTET is a meaningful SALT-cap workaround for high earners

• Consider if operating in Chicago metro

• You live or operate primarily in Illinois — forming locally avoids foreign qualification costs and compliance in multiple states.