Noun. 1. orthoclase-a white or colored monoclinic feldspar. feldspar, felspar-any of a group of hard crystalline minerals that consist of aluminum silicates of potassium or sodium or calcium or barium.rÂ·thoÂ·clase. A type of feldspar consisting of potassium aluminum silicate. Orthoclase is typically white, pink, yellow, or brown, but it can also be colorless. It is especially common in igneous rocks.
Year of Assessment. 'Year of Assessment' (YA) refers to the year in which income tax is calculated and charged. The assessment is for the income earned in the preceding year, starting on 1 Jan and ending on 31 Dec. Example: For YA 2017, the assessment is for income earned from Jan to Dec 2016. Back to top.
Special assessment tax. For the fee that must be paid by U.S. federal offenders, see Special assessment on convicted persons. Special assessment is the term used in the United States to designate a unique charge that government units can assess against real estate parcels for certain public projects.