The Canada Revenue Agency publishes, on a regular basis (they're now up to the 119th edition), a document entitled "Payroll Deductions Formulas". This document contains all of the formulas needed to calculate payroll deductions collected by the CRA: Canada Pension Plan, Employment Insurance, and Income Tax. As someone running a small business in Canada and not wanting to use an external payroll provider, I implement these formulas myself in a spreadsheet. Unfortunately, like most aspects of th...