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.
Customers who have been asked by HM Revenue and Customs (HMRC) to submit a Self Assessment tax return through a notice to file. This measure clarifies the time allowed for making a self-assessment. This is 4 years from the end of the tax year to which the self-assessment relates. This is the same time limit as for assessments by HMRC. The measure seeks to make clear the amount of time a customer has to submit a self-assessment.