An Arkansas contractor taking work in Connecticut deals with the same four questions everywhere: who licenses the trade, when a licence is actually required, when workers compensation kicks in, and where the business registers. Below is Connecticut's answer to each, with the agency's own link.
Licensing
Connecticut Department of Consumer Protection (DCP)
Home Improvement Contractor registration ($220 per year, $20,000 liability insurance) required for residential work over $200; new home construction contractors register separately. Major Contractor license (DCP Occupational & Professional Licensing) covers structural work above CGS 29-276b thresholds. Trade-licensed work exempt from HIC.
Workers compensation
Connecticut Workers' Compensation Commission
All Connecticut employers must carry workers' compensation insurance for employees, with few exceptions; corporate officers and LLC members may elect exclusion, and sole proprietors must opt in.
https://portal.ct.gov/wcc/knowledge-base/articles/employers/workers-compensation-insurance
Business registration
Connecticut Secretary of the State, Business One Stop (business.ct.gov)
Tax registration
Connecticut Department of Revenue Services (DRS), myconneCT
All building contractors, including subcontractors, must obtain a DRS Sales and Use Tax Permit before providing any services.
https://portal.ct.gov/drs/businesses/new-business-resource-center/registering-with-drs
New hire reporting
Most states require newly hired employees to be reported within a short window of their start date.
https://business.ct.gov/knowledge-base/articles/new-hire-reporting
Colorado · All fifty states · Delaware
Starting or running the business itself is covered in the contractor business guide. Arkansas licence records for Benton and Washington counties are in the contractor directory.