An Arkansas contractor taking work in Delaware 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 Delaware's answer to each, with the agency's own link.
Licensing
Delaware Division of Revenue (contractor business license); Division of Professional Regulation (trade licenses)
No general-contractor trade license; any contractor doing business in Delaware must register with and obtain a Division of Revenue business license (resident or non-resident contractor package via Delaware One Stop). Non-resident contractors face bonding rules. DPR licenses electricians, plumbers, HVACR.
https://revenue.delaware.gov/business-tax-forms/contractors-resident-and-non-resident
Workers compensation
Delaware Department of Labor, Division of Industrial Affairs (Office of Workers' Compensation)
Employers with one or more employees must carry workers' compensation; farm workers exempt. Construction-industry employers cannot be treated as independent contractors; they are deemed employers.
Business registration
Delaware Division of Corporations (Department of State)
Tax registration
Delaware Division of Revenue
Contractors must register and obtain a Delaware business license through One Stop; non-resident contractors have additional bond requirements.
New hire reporting
Most states require newly hired employees to be reported within a short window of their start date.
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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.