Instead of filling out a 1099, when you hire Canadian contractors, you should request a completed W-8BEN from them. This form ensures compliance with the IRS and the Canada-US tax treaty; without it, you are required to withhold and remit 30% tax on all contractor earnings.
You likely need to set up your own US company and pursue an E-2 visa to work in the US as an independent contractor.
Step 1: Fill out Form T1, which is called the General Income Tax and Benefit Return. You'll list your independent contractor income on Line 104. As an independent contractor, the company that hires you for your services will fill out a T4A slip and send it to the CRA. They'll also send a copy of it to you.
Completing your tax return Enter on line 10400 of your return the amount of your foreign employment income (in Canadian dollars) that is not included on a T4 slip. (If your foreign income is included on a T4 slip, see line 10100.)
The IRS requires a flat 30% withholding on ALL types of payments to foreign national individuals UNLESS: The individual has a U.S. tax identification number (SSN or ITIN) and qualifies for a tax reduction under the tax treaty between the U.S. and their country of tax residency.