Assessments: What determines when I am taxed for additions or improvements to my property?

(From the DRA Website)

Any structure, improvement or addition to the property determined to be in place ON APRIL 1ST is taxed in the current tax year, and is treated as having been in place for the entire year, even though it may not have been in place for a significant period of time. Structures, improvements or additions made AFTER APRIL 1ST are treated as though they did not exist in the current tax year, and are taxed in the following year.