I bought a truck in 2015. In 2017 I was promoted and I became eligible to use the same vehicle for work. What date do my interest payments commence on? 2015 or 2017?

Hi, if the vehicle became an eligible deduction in 2017, then you are able to claim eligible expenses starting then. Keep in mind that if the vehicle is used for both personal and business purposes you can only deduct that amount that was related to your income. There's great information on eligible vehicle expenses here: https://www.canada.ca/en/revenue-agency/services/tax/individuals/topics/about-your-tax-return/tax-re...