If you want to have more tax deducted at source, fill out section "Additional tax to be deducted" on the federal Form TD1.
You may ask to have less tax deducted at source if you are eligible for deductions or non-refundable tax credits that are not listed on this form (for example, periodic contributions to a registered retirement savings plan (RRSP), child care or employment expenses, charitable donations, and tuition and education amounts carried forward from the previous year To make this request, fill out Form T1213, Request to Reduce Tax Deductions at Source, to get a letter of authority from your tax services office. Give the letter of authority to your employer or payer. You do not need a letter of authority if your employer deducts RRSP contributions from your salary.
To get our forms and publications, go to canada.ca/cra-forms-publications or call 1-800-959-5525.
Personal information (including the SIN) is collected for the purposes of the administration or enforcement of the Income Tax Act and related programs and activities including administering tax, benefits, audit, compliance, and collection. The information collected may be used or disclosed for purposes of other federal acts that provide for the imposition and collection of a tax or duty. It may also be disclosed to other federal, provincial, territorial, or foreign government institutions to the extent authorized by law. Failure to provide this information may result in interest payable, penalties, or other actions. Under the Privacy Act, individuals have a right of protection, access to and correction of their personal information, or to file a complaint with the Privacy Commissioner of Canada regarding the handling of their personal information. Refer to Personal Information Bank CRA PPU 120 on Info Source at canada.ca/cra-information-about-programs.