What Constitutes Doing Business in Connecticut?

A company is doing business in Connecticut when its activities in the state go beyond isolated or passive contacts. Connecticut actually applies two overlapping standards: one decides whether you need a certificate of authority from the Secretary of the State, and the other decides whether you owe corporation business tax, sales tax, or payroll withholding. You can trigger tax obligations without needing to register, and you can need to register without owing much tax, so both tests matter.

What Pushes a Company Into Registration Territory

Connecticut requires every foreign corporation to obtain a certificate of authority before transacting business in the state, and the same principle applies to foreign LLCs and partnerships.¹ The statute doesn’t offer a bright-line test. Courts look at the pattern: how regular the activity is, how substantial, and how closely tied to Connecticut.

Some activities almost always cross the line. Leasing office space. Operating a retail location. Employing workers who perform their jobs in Connecticut. Negotiating and signing contracts inside the state. Providing ongoing services to Connecticut customers. The more continuous and systematic the activity, the stronger the case that you’re transacting business.

A single remote employee working from a Connecticut home office can be enough on its own. Work being physically performed in the state creates nexus even if the employee never interacts with Connecticut customers or generates revenue locally. Using a Professional Employer Organization doesn’t change that: a PEO handles payroll administration but doesn’t absorb your registration obligations, so you still need to register in every state where your workers sit.

Activities That Fall Below the Threshold

Section 33-920 lists activities that don’t count as transacting business. These safe harbors give companies room to have limited Connecticut contacts without registering:¹

Owning real or personal property in Connecticut without any other activity.
Maintaining or defending a lawsuit.
Holding board or shareholder meetings in the state.
Maintaining bank accounts in Connecticut.
Keeping transfer agents, registrars, or depositaries for the company’s own securities.
Selling through independent contractors rather than employees.
Soliciting or obtaining orders in Connecticut, as long as those orders must be accepted outside the state before they become binding.
Creating or acquiring debts, mortgages, or security interests in property, and collecting on or enforcing them.
A single transaction completed within 30 days that isn’t part of a repeated pattern.
Conducting business in interstate commerce, without more.

The statute says explicitly that this list is not exhaustive, so other low-level contacts may also fall below the line. But read each safe harbor narrowly. The moment your activity moves past what the exemption covers — for example, you own property and then start actively managing it to generate rental income — the exemption may stop protecting you.

Tax Nexus Is a Separate Question

Here is where companies most often get caught out. Connecticut’s tax statutes use a broader definition of “doing business” than the registration statute. The Department of Revenue Services considers a corporation to be carrying on business if it owns or leases real property in the state, maintains an office, sells tangible personal property, performs or solicits orders for services, or keeps inventory in a public warehouse.² You might not need a certificate of authority but still owe corporation business tax.

The corporation business tax rate is 7.5% of net income from business transacted within the state.³ Corporations with a “substantial economic presence” in Connecticut may need to file even without any physical footprint, under the state’s economic nexus doctrine for income tax purposes.²

Payroll Withholding

Any employer with employees working in Connecticut must withhold state income tax from their wages and remit it to the Commissioner of Revenue Services.⁴ The company must also contribute to the state’s unemployment insurance program. These obligations start with the first Connecticut employee on payroll, whether or not the company has registered as a foreign entity.

Sales Tax and Economic Nexus

Connecticut requires out-of-state sellers to collect sales and use tax once they meet both of two thresholds in a calendar year: at least $100,000 in gross revenue from Connecticut sales and at least 200 separate transactions with Connecticut buyers. Both conditions have to be satisfied. Meeting only one doesn’t trigger the obligation. This framework follows the U.S. Supreme Court’s 2018 decision in South Dakota v. Wayfair, Inc.

Marketplace facilitators sit under a different rule. A platform that facilitates at least $250,000 in retail sales during the prior twelve-month period must collect and remit sales tax on behalf of its marketplace sellers.⁵ If you sell through Amazon or Etsy, the platform handles collection. If you also sell directly to Connecticut customers outside the marketplace, you still have to run your own numbers against the economic nexus thresholds.

Remote Workers and the Convenience-of-Employer Rule

Connecticut applies a version of the “convenience of the employer” rule that can surprise out-of-state companies. Wages earned by a nonresident employee are sourced to Connecticut — the employer’s location — unless the employee works remotely out of necessity for the employer rather than for personal convenience.⁶

Connecticut applies the rule only when the employee’s home state also has a similar convenience rule. The states that trigger it are Arkansas, Delaware, Nebraska, New York, and Pennsylvania.⁶ A Connecticut-based company with a New York remote employee working from home for personal convenience can see those wages taxed by Connecticut. If the same employee lived in a state without a convenience rule, the rule wouldn’t apply.

Even outside the convenience rule, a single remote employee working from Connecticut can create nexus for an out-of-state employer. The physical presence of that work is enough to trigger payroll withholding, and potentially registration, whether or not the employee generates any Connecticut revenue.

What Registration Involves If You Cross the Line

Foreign corporations apply for a certificate of authority by filing an application with the Secretary of the State. It requires the corporation’s name, state of incorporation, date of incorporation, principal office address, and the name and Connecticut address of a registered agent.⁷ The filing fee is $385 for a foreign stock corporation.⁸ Nonstock corporations pay $40. Foreign LLCs file a foreign registration statement with a $120 fee.⁹

Every foreign entity must appoint a registered agent with a physical Connecticut address. The agent receives service of process — lawsuits and official notices — and forwards them to the company.¹⁰ A company officer who lives in Connecticut can serve, or you can designate the Secretary of the State, or hire a commercial registered agent service.

Penalties for Operating Without Authority

A foreign corporation that transacts business in Connecticut without a certificate of authority faces a $300 penalty for each month or partial month of noncompliance.¹¹ On top of that, the company owes all fees and taxes it would have paid had it registered, plus interest and penalties on those amounts. The monthly penalty alone adds up to $3,600 a year before back taxes.

There is one grace period worth knowing. A corporation that obtains its certificate of authority within 90 days of starting to transact business in Connecticut is not liable for the $300 monthly penalty.¹¹ Back taxes and fees still apply, but catching the issue early can save thousands. If you realize you should have registered, move quickly.

The other major consequence is losing access to Connecticut courts. An unregistered foreign corporation cannot maintain a lawsuit in any Connecticut court until it obtains a certificate of authority.¹¹ The same restriction extends to successors and assignees of causes of action that arose while the company was unregistered. A court can stay a proceeding while it decides whether the company needs a certificate. Failing to register doesn’t invalidate contracts, and it doesn’t stop the company from defending itself in court, but it effectively locks the company out of going on offense until it gets compliant.

Regulatory agencies add another layer. Licensing bodies can issue cease-and-desist orders, revoke permits, or impose additional sanctions on businesses operating without proper authority. Companies in heavily regulated industries such as healthcare, finance, and construction face the steepest exposure, including potential personal liability for corporate officers who knowingly operate out of compliance.

1
Justia. Connecticut Code 33-920 – Authority to Transact Business Required
2
Connecticut Department of Revenue Services. Corporation Business Tax Information
3
FindLaw. Connecticut Code 12-214 – Tax Rate
4
FindLaw. Connecticut Code 12-707 – Payment to Commissioner of Taxes Withheld by Employers
5
FindLaw. Connecticut Code 12-408e – Marketplace Facilitator Tax Collection
6
Connecticut General Assembly. Convenience of the Employer Rule
7
Justia. Connecticut Code 33-922 – Application for Certificate of Authority
8
Secretary of the State of Connecticut. Application for Certificate of Authority – Foreign Corporation
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Secretary of the State of Connecticut. Foreign LLC Forms and Fees
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Justia. Connecticut Code 33-929 – Service of Process
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Justia. Connecticut Code 33-921 – Consequences of Transacting Business Without Authority