Webto calculate net pay, subtract the sum of your deductions from your gross pay. Use the following equation to calculate your net pay: Weba step by step guide on how to calculate payroll manually with minimal errors and 100% compliance. Read on for formulas and best practices. Webgross annual income is the earnings you receive in one financial year before any deductions. Here are some income sources to include: Webcalculating gross salary in excel involves summing up an employee’s basic salary, allowances, bonuses, and any other earnings before deductions.