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 tax year 2014 to 2015 customers will have until 5 April 2019 to submit a self-assessment; for the tax year 2015 to 2016 customers will have until 5 April 2020 to submit a self-assessment; The 4 year time limit applies to everyone and those that are currently outside the time limit have notice to put in their self-assessment by 5 April 2017. Current law. The current law is contained at section 34 of the Taxes Management Act 1970 (TMA).