Some contractors must obtain licenses if they intend to do home improvements or construction work that exceed a certain dollar amounts. However, not every state sets limits for its contractors; some only require local licenses. In states like Delaware, you must have a contractor's license before you can bid on a job over $50,000.

Special Contractor's Licenses

In Montana, you only have to have a state license if you intend to do government work. In Nebraska, a license is only required for journeyman electricians. In Georgia, only plumbing, electrical and HVAC jobs need to be licensed. Idaho requires contractor's licenses from HVAC workers and electrical contractors. In Illinois, plumbing, roofing and electrical work all require state licensing. Only HVAC work requires a contractor's license in Kentucky. Vermont requires a general business license, while South Dakota requires a license for water and sewer work.

State Licenses

Florida, Louisiana, Colorado, Connecticut, Kansas, Indiana, Kansas, Missouri, New Hampshire, New York, Ohio, Pennsylvania and Wyoming don't require a specific state license for contractors. Before starting a project, though, check local ordinances to see what licenses you need from your city or county. Even if you have a state license from a state that requires one, check local regulations. Sometimes multiple licenses are required.

$50,000 and Up

Mississippi requires residential contractors involved in projects costing $50,000 and up to obtain a license. If the project exceeds $100,000 and involves constructing a building, you must apply for a building contractor license instead. Alabama requires a general contractor license when a project goes over $50,000. When calculating the cost of a project, you must add the materials and labor to determine whether you need a license. If a project is less than $50,000, both Mississippi and Alabama have alternate licenses that must be obtained.

Under $50,000

Alabama and Mississippi require special licensing of anyone doing home improvements of more than $10,000. Arkansas asks that contractors doing more than $20,000 worth of work obtain a license. California requires jobs over $500 to be licensed, and North Carolina requires licensing for jobs over $30,000. West Virginia requires licensing for jobs over $1,000, while Minnesota requires that people doing projects over $15,000 be licensed. All other states have licenses for various trades -- and in many states, where you register varies. In Washington state, for example, you must register with the State Department of Labor and Industries Contractor Registration Division.