Connecticut contrasts between "major contractor" from "small contractor." A significant contractor is licensed to operate in institutional homes (care homes, jails, etc.), hotels/motels, multi-family homes, and other big sites. A small contractor is licensed to operate in private houses and small multi-family units. A license is necessary in case the job exceeds $200.00 for one job or if the annual job exceeds $1,000.00 total.
License search: https://www.elicense.ct.gov/Lookup/LicenseLookup.aspx