Do you have to file a Canadian return

You must file a return for 2015 if any of the following situations apply:
You have to pay tax for 2015.
You have received a request to file a return for 2015.
You and your spouse or common-law partner elected to split pension income for 2015.

You received working income tax benefit (WITB) advance payments in 2015.
You disposed of capital property in 2015 (for example, if you sold real estate or shares) or you realized a taxable capital gain (for example, if a mutual fund or trust attributed income to you, or you are reporting a capital gains reserve you claimed on your 2014 return).
You have to repay any of your old age security or employment insurance benefits.
You have not repaid all amounts withdrawn from your registered retirement savings plan (RRSP) under the Home Buyers’ Plan or the Lifelong Learning Plan.
You have to contribute to the Canada Pension Plan (CPP). This can apply if for 2015 the total of your net self-employment income and pensionable employment income is more than $3,500.
You are paying employment insurance premiums on self-employment and other eligible earnings.

Even if none of these requirements apply, you can file a return for other reasons: