Before you start

An SSN or ITIN
Form W-4 with your employer for federal withholding
Arizona Form A-4 for state withholding — you must choose a percentage
Records of foreign income and foreign financial accounts

Step-by-step

1
Complete the W-4 and the Arizona A-4 on day one
Arizona's withholding certificate asks you to select a withholding percentage rather than deriving it from the federal form. If you do not file an A-4 the employer applies a default rate, which is frequently wrong for your situation. It takes two minutes and it prevents an April surprise.
Via employerWho: YouFirst week of employment
2
Determine your US tax residency
The substantial presence test counts weighted days across three years to decide whether the US taxes your worldwide income or only US-source income. Certain students and scholars are exempt from counting days for a period. Your visa category does not settle this.
OnlineWho: You
3
Check for an applicable tax treaty
The US has income tax treaties with around 70 countries. Arizona begins from federal adjusted gross income, so a federal treaty exclusion generally flows through to the state return — unlike California, which ignores treaties entirely. For a researcher or graduate student that is a meaningful difference between neighbouring states.
OnlineWho: You
4
File federal and Arizona returns by 15 April
The tax year is the calendar year. Because Arizona applies one flat rate to a federal starting point, the state return is among the quickest in the country and often takes minutes once the federal one is done.
OnlineWho: YouBy 15 April annually
5
Look at Arizona's tax credit programmes before you donate anything
Arizona offers dollar-for-dollar state tax credits for donations to qualifying charitable organisations, foster care agencies, public school extracurricular fees and private school tuition organisations. Within the limits, these reduce your Arizona tax bill by the full amount donated — you choose where a portion of your state tax goes rather than paying it. Very few states do this and almost no newcomer knows.
OnlineWho: You
6
File an FBAR if foreign accounts exceed $10,000
Aggregate foreign financial account balances above $10,000 at any point in the year trigger a FinCEN filing, separate from your tax return. An ordinary current account at home is often enough to cross it.
OnlineWho: You

Documents you’ll need

Form W-2 from each employer, issued by 31 January
Form 1099s for freelance, interest and investment income
Passport and travel history for the substantial presence day count
Foreign account statements for FBAR reporting
Receipts for Arizona credit-eligible donations, if claiming them

Things most newcomers don’t know

Arizona's dollar-for-dollar tax credits let you direct where part of your state tax goes.

Donations to qualifying charitable organisations, foster care charities, public school extracurricular programmes and private school tuition organisations generate credits that reduce your Arizona tax bill by the full amount given, up to published limits. This is a credit, not a deduction — a $400 qualifying donation reduces the tax owed by $400. Within the caps it costs you nothing and redirects money you were going to pay anyway.

Source: Arizona Department of Revenue — tax credits

The rental tax that used to appear on every Phoenix lease was abolished in 2025.

Until the end of 2024, Arizona cities charged a transaction privilege tax on residential rent — around 2.3% in Phoenix — collected by the landlord and added to the monthly bill. State law removed it for long-term residential rentals from 1 January 2025. Older leases, older listings and older relocation guides still quote it. If a landlord is still adding city rental tax to a lease of 30 days or more, question it.

Source: Arizona Department of Revenue — residential rental guidelines

The 10% assessment ratio is why Arizona property tax is so much lighter than Texas's.

Arizona assesses owner-occupied residential property at 10% of full cash value and the state constitution caps primary property taxes on such a home at 1% of that full cash value. Effective rates land well under 1% of market value — roughly a third of what a comparable Dallas or Houston house pays. Someone comparing 'no income tax Texas' against 'income tax Arizona' on headline rates alone reaches the wrong answer for a homeowner.

Source: Arizona Department of Revenue — property tax

Arizona does not observe daylight saving, which matters more than it sounds.

Phoenix stays on Mountain Standard Time all year, so it shares a clock with Los Angeles from March to November and with Denver from November to March. For anyone working with an east coast or European team, the meeting window shifts by an hour twice a year without your clock changing — and every recurring calendar invite you accepted before the move will drift. Fix the timezone on your calendar rather than the individual events.

Source: community-reported

Common mistakes to avoid

Not filing an Arizona A-4 and letting the employer apply a default withholding percentage.
Donating to charity without checking whether it qualifies for a dollar-for-dollar Arizona credit.
Accepting a lease that still adds city rental tax to a long-term residential tenancy.
Comparing Arizona against Texas on income tax alone and ignoring the property tax difference.
Believing a filing extension also extends the payment deadline — it does not.

Some of this may be out of date. Spotted something inaccurate? Help us keep it right for the next newcomer.