Locum Tenens Taxes in Arizona

A nonresident with Arizona-source income files Form 140NR, the nonresident personal income tax return. Arizona-source income includes wages and business income from services physically performed in Arizona, so both W-2 and 1099 locum work at Arizona facilities counts. The filing thresholds are indexed and prorated for nonresidents based on the Arizona share of total income; they're low enough that any meaningful assignment clears them, so the practical rule is simple: paid Arizona work means a 140NR.

Part-year residents (physicians who actually move into or out of Arizona mid-year) file Form 140PY instead, paying as a resident for the resident portion and on Arizona-source income for the rest. The mechanics on the 140NR are straightforward: report federal income, carve out the Arizona-source share, take prorated deductions, and apply the flat 2.5%.

Arizona follows the standard rule: income from personal services is sourced to where the services are physically performed. Days worked at a Flagstaff hospital create Arizona-source income whether you're paid W-2 by an agency in Dallas or 1099 through your own S-corp in Nevada. For multi-state years, allocate by contract records where possible and working-day ratio otherwise, and keep the day log current.

Telehealth wrinkle: if you're physically in Arizona while seeing patients located elsewhere, the services are still being performed in Arizona for sourcing purposes. Physicians who winter in Arizona and run telemedicine shifts from a rental should assume those days generate Arizona-source income (and count toward the residency clock in Section 03).

Arizona treats you as a resident if you're domiciled there, and it presumes residency if you spend more than nine months of the tax year in Arizona. Residents are taxed on all income from all sources, not just the Arizona slice. That's the trap for locums who love the Southwest: a November-through-April stretch of Phoenix and Tucson assignments, plus a summer contract that runs long, plus personal time in a state you enjoy, and suddenly your day count is in dangerous territory.

The presumption is rebuttable, and domicile (your permanent home, where you intend to return) is the real test. But rebutting a presumption is exactly the fight you don't want. If Arizona is going to be a big part of your year, keep the evidence of your out-of-state domicile strong: home, driver's license, voter and vehicle registration, professional licenses, and genuine return trips. And know your day count before December, when there's still time to shift a contract.

Arizona doesn't have traditional reciprocity agreements like the PA/OH networks. What it has is a withholding accommodation: W-2 employees who are residents of California, Indiana, Oregon, or Virginia can file Arizona Form WEC to be exempted from Arizona withholding, because the credit mechanics for those states run in reverse (more below). That's a payroll convenience, not a tax exemption, and it does nothing for 1099 physicians, who have no withholding to exempt in the first place.

The reverse credit is the piece worth understanding cold, because AZ-CA is the single most common cross-border pairing for Southwest locums. Normally, your home state credits you for tax paid to the state where you worked. Between Arizona and California the rule flips: a California resident working in Arizona claims the credit for the double-taxed income on the Arizona return (Form 309), reducing the Arizona tax, while paying California in full. An Arizona resident working in California claims the credit on the Arizona resident return for tax paid to California under Arizona's normal credit rules. The result in both directions: the higher California rate effectively wins, and the paperwork lands somewhere unfamiliar.

W-2 agencies withhold Arizona tax based on your Form A-4 election (Arizona uses percentage-of-gross elections rather than allowances). 1099 physicians get nothing withheld and cover the liability through quarterly estimates on Form 140ES. At 2.5%, the amounts are manageable: $2,500 per $100,000 of Arizona-source net income. Set the transfer up once and the state stays painless.

There are no municipal income taxes and no separate local filings, which is part of why we describe Arizona as one of the lowest-friction states a locum can add to the calendar. One state return, one flat rate, done.

Arizona adds almost no friction to the standard locum S-corp play. There's no franchise tax and no entity-level minimum tax on S-corps; the corporation files an Arizona S-corp return and the income flows through to shareholders, with nonresident shareholders picking up the Arizona-source share. The usual break-even analysis (payroll costs and compliance versus self-employment tax savings) applies without a state-specific penalty.

Arizona also offers a pass-through entity tax election, currently assessed at 2.5% (it launched at 4.5% and now tracks the individual rate). The entity pays the Arizona tax, deducts it federally, and owners claim a matching credit. Because the rate is low and the federal SALT cap now sits at $40,000 through 2026, many locums already deduct their full state tax without the election; it earns its keep mainly for very high earners or physicians with big state bills elsewhere. Worth a check, not a reflex.

One coordination note: if your S-corp elects Arizona's PTET while you're a resident of another state, confirm your home state will credit an entity-level tax before electing. Most states now do; a few, like Pennsylvania for partnership-form entities, have quirks.

Illustrative example, not a specific client outcome. A hospitalist lives in San Diego (California resident) and picks up $100,000 of 1099 net income from winter assignments in Yuma and Phoenix. Assume her California marginal rate on this income is roughly 9.3%. Here's how the reverse credit sorts it out.