Payments to a foreign corporation in exchange for personal services performed in the US by either a US citizen or alien is considered to be US-sourced income and is usually subject to withholding. (Can be wages or self-employment income.)
All persons ('withholding agents') making US-source fixed, determinable, annual, or periodical (FDAP) payments to foreign persons generally must report and withhold 30% of the gross US-source FDAP payments, such as dividends, interest, royalties, etc.
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.
Exemption from withholding To qualify for this exempt status, the employee must have had no tax liability for the previous year and must expect to have no tax liability for the current year. A Form W-4 claiming exemption from withholding is valid for only the calendar year in which it's furnished to the employer.
Payments subject to withholding include compensation for services, interest, dividends, rents, royalties, annuities, and certain other payments. Tax is withheld at 30% of the gross amount of the payment.
In order to be exempt from FICA tax, a foreign national must be: A nonresident alien for tax purposes. Present in the United States under an F, J, M or Q immigration status. Performing services in ance with the primary purpose of the visa's issuance (i.e. F-1 student working as a TA)
Self-employment Tax: Even though the Canadian company doesn't issue a 1099,you are still responsible for reporting all your income, including this, on your US tax return.