Calculate the deduction separately for each part of capital works that meets the description of your area.
Multiply your construction expenditure by the applicable rate and by the number of days in the income year in which the fund owned, leased or held your area and used it in a relevant way. Divide that amount by the number of days in the income year. See section 43-210 of the ITAA 1997.
Apportion the amount if your area is used only partly to produce assessable income (or if relevant partly for the purpose of conducting R&D activities).
There is a basic entitlement to a rate of 2.5% for parts used as described in table 43-140 (current year use). The rate increases to 4% for parts used as described in table 43-145 (use in the 4% manner).