Generally, property improvements which require a permit to install are included in a property tax assessment. My guess is that a carport structure which is designed and installed to meet building codes will be considered a permanent structure and subject to property tax. If you ask a city/county planning zoning officer, the building permit department and the county tax assessor for your area, you will likely get to the correct answer. If you appreciate an answer, please give "thumbs up". For the most helpful answer, please say thanks with a "best answer" click.