Getting Started

Register your new business with the Connecticut Department of Revenue Services (DRS) using myconneCT, the Department’s online tax filing portal where you can also view/update your account, file returns, make payments, and communicate with DRS.

DRS has a variety of tutorials and frequently asked question (FAQs) on myconneCT that can help with registering and answering many of the common questions.

Business Tax Filing Requirements

• Sole Proprietorship
• Corporation
• Pass-Through Entities
  • Partnership
  • S Corporation
  • Limited Liability Company
  • Limited Liability Partnership 

We explain the Connecticut tax requirements that apply to each business structure below. For federal tax information and filing requirements, contact the Internal Revenue Service (IRS).

Sole Proprietorship

Income derived from your business operating in Connecticut is included on federal Form 1040. The federal adjusted gross income is the starting point for completing your Connecticut income tax return. Use Form CT-1040, Connecticut Resident Income Tax Return, or Form CT-1040NR/PY, Connecticut Nonresident and Part-Year Resident Income Tax Return, to report income from a sole proprietorship.

Connecticut residents report their income on Form CT-1040. Nonresidents and part-year residents use Form CT-1040NR/PY.

Nonresident individuals conducting business in Connecticut are required to report income derived from or connected with Connecticut sources. This includes income from a business, trade, profession, or occupation carried on in Connecticut; income from any interest in real estate or personal property located in Connecticut; income from intangible personal property to the extent it is used in a business, trade, profession, or occupation carried on in Connecticut; and any gain or loss from the sale or disposition of an interest in an entity that owns property in Connecticut.

For more information on the Connecticut Individual Income Tax, visit the Connecticut Resident Tax Information.

Corporation

C Corporations: Every C corporation and every other entity taxed as a C corporation for federal income tax purposes must file a corporation business tax return with DRS.

• Every corporation (or association taxable as a corporation) that carries on business or has the right to carry on business in Connecticut must complete a registration application and file Form CT‑1120, Corporation Business Tax Return. Any corporation dissolved or withdrawn from Connecticut is subject to the Corporation Business Tax up to the date of dissolution or withdrawal.

• Groups of companies with common ownership that are engaged in a unitary business, where at least one member of the group is subject to the Corporation Business Tax, are required to calculate their tax liability on a combined unitary basis on Form CT‑1120CU, Combined Unitary Corporation Business Tax Return. 

For more information on the Connecticut Corporation Business Tax, visit the Connecticut Corporation Business Tax Information.

Pass-Through Entities

Pass-through entity (PE) means a partnership or an S corporation.

Partnership means and includes a general partnership, limited partnership, limited liability partnership, publicly traded partnership, limited liability company (LLC) treated as a partnership for federal income tax purposes, or other entity treated as a partnership for federal income tax purposes.

Parent pass‑through entity (parent PE) is a PE which is a member of another PE. A PE may be both a parent PE (with respect to one or more PEs) and a subsidiary PE (with respect to one or more PEs).

Subsidiary pass‑through entity (subsidiary PE) is a PE which has at least one member which is itself a PE. A PE may be both a subsidiary PE (with respect to one or more PEs) and a parent PE (with respect to one or more PEs).

S corporation means a corporation which is an S corporation for federal income tax purposes.

For more information on the Connecticut Pass-Through Entity Tax, visit the Connecticut Pass-Through Entity Tax Information.