All property shall be assessed according to its just value as follows:
(1) Real property, on January 1 of each year. Improvements or portions not substantially completed on January 1 shall have no value placed thereon. “Substantially completed” shall mean that the improvement or some self-sufficient unit within it can be used for the purpose for which it was constructed.
(2) Tangible personal property, on January 1, except construction work in progress shall have no value placed thereon until substantially completed as defined in s. 192.001(11)(d).