Total income refers to the income you need to pay taxes. The tax rate is a proportion set by the government, usually expressed as a percentage. For example, if the tax rate is 10%, then every 100 yuan of income needs to pay 10 yuan tax. In addition, there are some other related concepts and formulas. The calculation formula of interest is: interest = principal × interest rate× time. The principal here is your initial investment, the interest rate is the annualized rate of return provided by banks or financial institutions, and the time is the length of time in years.