Claiming a person as a dependant does not mean they don't file their own income tax return. Everyone who earns income needs to file a personal tax return, even when someone else (for example, a parent or grandparent) claims them as a dependant. Even if the defendant has no income, they are still eligible for certain credits, such as GST/HST or other federal or provincial credits.

Anyone who meets the Canada Revenue Agency's (CRA) criteria for filing is required to file a tax return. This includes minors (children younger than 18).

If you have any dependents who meet any of the CRA criteria for filing, they'll need to file a separate return. 

Are minors (those under 18) required to file a tax return?

As per CRA: Minors may have taxes owing if they have earned more income than-

• The federal basic personal amount ($12,069 for 2019). or
• Your provincial Basic personal amount (which varies by province).

However, even if you are minor and didn’t earn enough income to owe taxes, it may still be beneficial to file a return. For instance, if you had income tax or CPP premiums deducted at the source, you may be eligible to receive those deductions back in the form of a refund.

For more information please click: Who has to file a tax return?