Before you start

An SSN or ITIN
Form W-4 with your employer for federal withholding
Form DE 4 with your employer for California withholding
Records of foreign income and foreign financial accounts

Step-by-step

1
Complete the W-4 and California's DE 4 on day one
California has its own withholding certificate, and its allowance rules differ enough from the federal form that copying your federal figures across produces the wrong withholding. Given how steep the state's brackets get, under-withholding here compounds quickly.
Via employerWho: YouFirst week of employment
2
Understand that California does not follow federal tax treaties
This is the most expensive single fact for an international arrival in California. Where New York and most states begin from federal adjusted gross income and therefore inherit a treaty exclusion, California does not conform to US income tax treaties — income excluded federally can still be taxable by California. If you are relying on a treaty article, get advice specific to California before your first return.
OnlineWho: You
3
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, which matters at Fresno State and UCSF Fresno. Your visa category does not settle this.
OnlineWho: You
4
Know what Proposition 13 does to your property tax
California caps property tax at roughly 1% of assessed value with limited annual increases, and reassesses to market value only on a change of ownership. Local voter-approved bonds and assessments sit on top. Two practical consequences in Fresno: your bill is anchored to a Valley purchase price rather than a coastal one, and two identical houses on the same street can carry very different bills depending on when each last sold.
OnlineWho: You
5
File federal and California returns by the deadlines
The tax year is the calendar year. California's return is filed with the Franchise Tax Board. The state's filing and extension rules are not identical to the federal ones, so check the FTB's current guidance rather than assuming the IRS calendar covers both.
OnlineWho: YouAnnually
6
File an FBAR if foreign accounts exceed USD 10,000
Aggregate foreign financial account balances above USD 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
Form DE 4 filed with your employer
Passport and travel history for the substantial presence day count
Foreign account statements for FBAR reporting

Things most newcomers don’t know

Same California tax, a much smaller base — that is the whole Fresno argument.

The 12.3% top rate, the millionaire surcharge and the uncapped State Disability Insurance are identical to San Jose's and Los Angeles'. What differs is what you are paying them on and what you pay locally: a one-bed at USD 1,100–1,450 rather than three or four times that, sales tax at 8.350% rather than 9%-plus across much of Los Angeles County, and a Proposition 13 base set by a Valley purchase price. The state takes the same percentage; the number it takes it from is smaller, and so is nearly every bill underneath it.

Source: California Franchise Tax Board and CDTFA

California does not conform to US tax treaties, and that catches internationals every year.

New York's return starts from federal adjusted gross income, so a treaty exclusion generally flows through to the state. California does not follow treaties at all, so income a treaty excludes federally can still be taxed by California. For visiting academics at Fresno State and UCSF Fresno, and for anyone relying on a treaty article, this is a real and recurring cost that almost no national relocation guide mentions.

Source: California Franchise Tax Board

No Californian city levies an income tax — the local money comes from sales tax and Proposition 13.

Unlike Ohio, Michigan, Kansas City or New York City, no California city taxes income. What varies locally is the district sales tax — CDTFA publishes the City of Fresno at 8.350% and unincorporated Fresno County at 7.975%, against a 7.25% statewide base — and what Proposition 13 froze into your property assessment. When comparing Californian cities, those two numbers are the local variables and the income tax is not.

Source: CDTFA — California city and county sales and use tax rates

Fresno sets no local minimum wage, which most large Californian cities do.

Los Angeles, San Jose, San Diego, San Francisco, Oakland, Pasadena and a long list of Bay Area cities have their own ordinances above the state rate. Fresno is not on that list, so the floor here is California's USD 16.90 statewide from 1 January 2026. That is the most immediately material fact on this page for anyone paid hourly, and it is invisible in any state-level guide.

Source: California Department of Industrial Relations, and the UC Berkeley Labor Center inventory of local ordinances

Common mistakes to avoid

Assuming a federal tax treaty exclusion carries over to California. It does not.
Copying federal W-4 allowances onto California's DE 4.
Comparing Californian cities on income tax, which is identical, rather than on sales tax and housing.
Expecting a local minimum wage ordinance because most big Californian cities have one — Fresno does not.
Assuming California's filing and extension rules mirror the federal ones.

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