Shel-lee is correct that some remodels do require a C of O, Where I live, for example, if you remodel more than 80% you need one. At that point you are basically redoing everything so nothing gets "grandfathered" in and everything has to be brought to code. Basically, a C of O says that everything meets all building codes current at the time the work was completed.
You should check with the county building department on this. The Certificate of Occupancy would have been required when the building was completed and therefore would already be in existence before the selling of the home.
Contrary to the first response you received, I would be careful in making this determination on my own. I believe there are some levels of remodel where a Certificate of Occupancy may be required. For example, a build out of attic space into living space would probably trigger the requirement for a Certificate of Occupancy. Seek the advice of a professional who is familiar with the building department requirements in your area, or go directly to the building department for this information.
Shel-lee Davis BRE #01817412
Real Estate Consultant
International Real Estate Specialist - IRESÂ®
Senior Real Estate Specialist - SRESÂ®
Certified Home Seller Advisor - CHSAÂ®
Certified Home Buyer Advisor - CHBAÂ®
Member - National Association of Certified Expert Advisors - NAEA
Certified Distressed Property Expert - CDPEÂ®
RE/MAX Estate Properties