If you need to file an adjusted return for the current year or a previous tax year, you must submit a TP-1.R Request for an Adjustment to an Income Tax Return.
You can obtain TP1.R-V form from Revenu Québec.
Complete the form, then send it (together with your supporting documents such as receipts, information slips, schedules, etc.), to the Revenu Québec office in your area. View a list of Revenu Québec offices.