Under US domestic tax laws, a foreign person generally is subject to 30% US tax on the gross amount of certain US-source income.
To change the amount of Arizona income tax withheld, an employee must complete Arizona Form A-4 and submit to his or her employer to choose a different withholding percentage. Employees may also request to have an additional amount withheld by their employer.
The form confirms that the contractor isn't a U.S. citizen and isn't working within the United States. If both of these things are true, the contractor isn't subject to American taxes. Without this form, you must withhold 30% of your payments to foreign contractors for taxes.
If the employee working in Arizona is not an Arizona resident, withholding of Arizona state income tax is required once the employee has been working in Arizona for 60 days. If both the employer and nonresident employee agree, withholding can start at the beginning of employment instead of waiting 60 days.
If you are a U.S. citizen or U.S. resident alien, you report your foreign income on your tax return where you report your U.S. income. That is, on line 1 of IRS Form 1040.
To choose the deduction, you must deduct foreign income taxes on Schedule A (Form 1040), Itemized Deductions. To choose the foreign tax credit, you generally must complete Form 1116 and attach it to your Form 1040, Form 1040-SR or Form 1040-NR.
Arizona determines state taxes using your federal adjusted gross income (AGI). Consequently, any foreign income excluded on your federal return will also be excluded from your Arizona return. If you need to file a federal return, you must also file an Arizona state return.