Today, it's possible to hire independent contractors from any part of the world, thanks to improvements in technology and communications. It's a great idea to consider Mexico if you're looking to expand your team. Its proximity and strong economic ties to the US are definite advantages.
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 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.