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.
For the 2016 year of assessment (1 March 2015 - 29 February 2016). 1  R73 650 if you are younger than 65 years. 2  If you are 65 years of age or older, the tax threshold (i.e. the amount above which income tax becomes payable) increases to R114 800. 3  For taxpayers aged 75 years and older, this threshold is R128 500.