The guidelines and requirements for registering a home kitchen as commercial vary from state to state; some states don't allow you to produce food in your home kitchen for commercial purposes under any circumstances. Other states allow you to register your home kitchen as commercial only if you are not producing any potentially hazardous foods for sale, or if you own and operate a farm, or if your sales volume does not exceed a certain amount.
Contact your local health department and find out whether you can license a home kitchen for commercial use. Research the guidelines and requirements and evaluate whether your vision of the business you want to run complies with their rules and regulations and, if not, whether you can adapt it to do so. Most states that do allow you to license your home kitchen for commercial use severely restrict the types of food you can produce there. In Maine, you can only license your home kitchen for commercial use if you are canning high-acid foods such as jams and pickles, or baked goods that don't contain fruit or savory fillings. if you want to prepare a wider range of foods, consider renting or building a separate commercial kitchen. Your state's Cooperative Extension Service can help you determine whether your business idea is appropriate for a licensed home commercial kitchen.
Upgrade any elements of your kitchen that do not meet local requirements. In most states, you will need to have screens on all windows and doors, an adequate supply of hot and cold water, as well as a hot water heater capable of heating your water to at least 120 degrees. If your home is outside the municipal water system, you will probably have to perform lab tests to document that your water supply is safe, and you may have to demonstrate that your septic system is adequate to handle the sewage and wastewater that your commercial kitchen will generate. Floors and counters should be smooth and easy to clean with a bleach solution and your bathroom must be sanitary. Your refrigerator must be able to hold foods at safe temperatures, generally 41 degrees or less.
If you're certain you can comply, complete the application and pay the licensing fee to register your home kitchen as commercial. You may have to prepare and include support materials such as verification that your water comes from an approved source, a list of venues where you will be selling your products and results of lab tests establishing that your food is not potentially hazardous.