Tax credits are provided through the income tax system. The value of a tax credit can increase the tax refund you receive, or reduce the tax amount you have to pay, if you owe taxes.
The student loan interest tax credit estimate provided through the Repayment Calculator is only an estimate of the annual tax credit amount that may be available, based on your outstanding loan debt, interest rate and repayment period. You can only claim interest paid in the year by you or a family member on government student loans. Interest paid on student loans issued by private banks and on other types of loans cannot be claimed. The actual value of your tax credit may vary depending on your personal circumstances.
If the total value of your tax credit is more than your income tax for the year, you won't get a refund for the difference. However, you can carry forward the unused amount and claim it in any of the next five years when you have income tax to apply it against.
To learn more about student loan interest tax credits and tax issues affecting students, please visit the Canada Revenue Agency website http://www.cra-arc.gc.ca/E/pub/tg/p105/.