Any new construction to your property that increases its market value must be reflected in your assessed value. This may include decks, patios, sun rooms, finished basements, expanding living space, etc. Our office receives copies of building permits which initiates a field inspection to verify the details of the new construction. The State of Illinois allows for an exemption on these improvements for a term of 4 years. The adjustment for this exemption will be applied on your tax bill. There is a $25,000 cap in assessed value (or $75,000 if full value) on the amount of value to be exempted.