Every town has a building department and its own building codes. Some towns require a Certificate of Occupancy Upon Resale, others don't. When you are buying a home, you need to find out what remodeling work has been done on the home and whether permits have been applied for and signed off on for each remodeling job in the house. Each town has its own requirements as to when it requires permits for certain renovations and upgrading. Permits are generally required for a new addition, renovating a kitchen or bathroom, replacing the furnace or hot water heater, updated plumbing or electrical, finishing the attic or the basement, installing central air conditioning. Repairs do not require permits but sometimes there's a question about whether a repair is so extensive that it qualifies as a renovation or upgrade. The application for the permit is made by the homeowner or his agent (an engineer, architect, plumber, electrician, or contractor). After the work is completed, it is the homeowner's responsibility to have the inspections made by the town to have the permits signed off, a written confirmation by the town that the work has been completed in accordance with the building codes. If you have found a home that you want to buy, review the Seller's Property Condition Disclosures to see if any renovations or upgrading is identified. Ask the seller about whether permits were taken out for the work that was done. If they were, get copies of the permits from the seller. Also, double-check with the town's building department as to whether permits are required for each of the alterations or upgrading that was disclosed and whether the seller took out and closed out the required permits. Never take a seller's word for it that all required permits were obtained. If permits were required but never obtained, you may want to walk away from the house. It is possible that the alteration was not done up to code. It is also possible that the alteration was done to code and the homeowner did not want to spend the money to hire a licensed contractor to perform the work. If a permit was required for work that was done in the house and never applied for, the seller will be required to get the permit and have the inspection done to close out the permit. Depending on the town, this may take longer than you are willing to wait. While the seller is getting the permit, you have a mortgage commitment that may be expiring or a rate lock that may be expiring or you may need to be out of your current residence in a hurry. It is smart to investigate this issue before you submit an offer to a seller. You don't want any nasty surprises once you have set the purchase wheels in motion.