What percentage do I choose for State Withholding tax ? (Arizona)

I just landed a new job in AZ , and I'm in the process of filling out my A4, but it has options for 0.8%, 1.3%, 1.8%, 2.7%, 3.6%, 4.2 % and 5.1%. Now, how do I decide which one to choose? (I'm an international student and working on CPT if that makes any difference)

Answer : 

Then even if you are a non US resident for federal tax purposes, you need to file your AZ return as a full year resident of AZ, Not a non-resident of AZ, so you need to file AZ form 140(as long as you need to file AZ return). So I guess you , as a new EE, need to complete A4 in the first five days of employment to select an Arizona withholding percentage. You may also have your employer withhold an extra amount from each paycheck. If you do not file this form, the department requires your employer to withhold 2.7% of your gross taxable wages. You may elect an AZ withholding percentage of zero if you expect to have no AZ income tax liability for the current year. AZ tax liability is gross tax liability less any tax credits, such as the family tax credit, school tax credits, or credits for taxes paid to other states. If you make this election, your employer will not withhold AZ income tax from your wages for payroll periods beginning after the date you file the form. Zero withholding does not relieve you from paying AZ income taxes that might be due at the time you file your AZ income tax return. If you have an AZ tax liability when you file your return or if at...Read More...