Form 540NR is California’s income tax return for nonresidents and part-year residents. You file it when you lived outside California for all or part of the tax year but earned income the state can tax, whether from a job performed in California, a rental property located there, a business operating in the state, or a short work trip to a California office. Nonresidents pay California tax only on income sourced to California; part-year residents pay on worldwide income for the months they lived in the state plus any California-sourced income from the months they did not.
Who Has to File Form 540NR
Two groups use this form. The first is nonresidents, meaning people whose permanent home is in another state but who received income tied to California during the year. The second is part-year residents, meaning people who established or gave up California residency partway through the year.
Whether you cross the filing threshold depends on your filing status, age, dependents, and total income from all sources worldwide, not just the California slice. For the 2025 tax year, a single nonresident under 65 with no dependents must file if total gross income from all sources exceeds $22,941 or California adjusted gross income tops $18,353.1Franchise Tax Board. Instructions for Form 540NR Nonresident or Part-Year Resident Booklet That worldwide-income piece catches people off guard: even a small amount of California income can trigger a filing requirement if your overall income is high enough.
You also have to file if you owe any California tax for the year, regardless of income level. That includes tax from a lump-sum distribution or the Alternative Minimum Tax. And if California tax was withheld from your pay or you made estimated payments to the state, filing a 540NR is the only way to get that money refunded, even if your income sits below the normal thresholds.1Franchise Tax Board. Instructions for Form 540NR Nonresident or Part-Year Resident Booklet
What Counts as California-Sourced Income
The central question on every 540NR is which dollars count as California-sourced. The state’s rule is that income is sourced to the place where the income-producing activity happens, not where the check arrives or where you live.
Wages and Remote Work
Compensation for services is sourced to the location where you physically perform the work.2State of California Franchise Tax Board. Part-Year Resident and Nonresident If you work for a San Francisco company but do all your work from a home office in Texas, that salary is not California-sourced and does not go on the 540NR. The employer’s location does not matter for employee wages.
That changes the moment you set foot in California to work. Spend two weeks at headquarters in March and another week in July, and the income allocable to those days is taxable by California. The FTB uses a “duty days” formula: divide the number of days you worked in California by your total working days for the year, then multiply by your annual compensation.2State of California Franchise Tax Board. Part-Year Resident and Nonresident Weekends and holidays don’t count unless you actually worked those days.
Business Income
If you operate a trade or business, income is sourced to California when the activity generating it happens in the state. A freelance consultant based in Oregon who flies to Los Angeles for a two-month project has California-sourced business income from that engagement. A business operating in multiple states apportions its income using factors like the share of sales, property, and payroll attributable to California.
Rental Income and Real Estate
Rental income and gains from selling real property are always sourced to the state where the property sits. Live in Nevada and own a rental in Sacramento, and every dollar of net rental income is California-sourced, as is any profit when you sell. There is no proration here. The property’s location controls.
Capital Gains and Investments
Gains from selling intangible property like stocks, bonds, and mutual funds are generally sourced to the taxpayer’s state of residence at the time of sale.3Legal Information Institute. California Code of Regulations Title 18 Section 17952 – Income From Intangible Personal Property A nonresident who sells stock in a California corporation usually owes California nothing on that gain.
The exception is “business situs.” If intangible property is used as capital in a California business or functions as an asset of a California operation, the income from it becomes California-sourced regardless of where you live.3Legal Information Institute. California Code of Regulations Title 18 Section 17952 – Income From Intangible Personal Property Selling an interest in a California-based partnership or LLC can also trigger California tax when the gain derives from the entity’s California operations.
How the Tax Calculation Works
California’s approach often produces a higher effective rate than people expect. The state does not simply apply its brackets to your California income. It calculates the tax you would owe if all your worldwide income were taxable by California, then charges you the share of that amount that matches your California income’s share of the total.4California Legislative Information. California Revenue and Taxation Code Section 17041
In practice, your worldwide income sets the rate, and that rate applies to your California-sourced income. Someone earning $300,000 total but only $50,000 from California does not get the low-bracket treatment a $50,000 earner would. They get taxed at the effective rate of a $300,000 earner, applied to the $50,000.
Taxpayers with taxable income over $1,000,000 also pay an additional 1% Mental Health Services Tax on the amount above that line, prorated through the same method.
Schedule CA (540NR)
The mechanical heart of the return is Schedule CA (540NR), which translates your federal numbers into California numbers. You start by entering your federal income amounts in Column A.5California Franchise Tax Board. Schedule CA (540NR) 2025 Columns B and C adjust for differences between federal and California tax law. Column D is your total income under California rules, as if you were a full-year resident.
Column E is where the sourcing happens. It captures only the income you earned while living in California (for part-year residents) plus income from California sources during periods of nonresidency.5California Franchise Tax Board. Schedule CA (540NR) 2025 The ratio of Column E to Column D is your proration percentage, which the FTB multiplies against the hypothetical full-year tax to get your actual liability.
Standard and Itemized Deductions
For 2025, California’s standard deduction is $5,706 for single filers and those married filing separately, and $11,412 for married couples filing jointly, heads of household, and qualifying surviving spouses. These are substantially lower than the federal figures, which surprises many filers. California does not conform to all federal itemized deduction rules, so if you itemize, the amounts can differ from your federal Schedule A.
Avoiding Double Taxation With Your Home State
When the same income gets taxed by both California and your home state, you can usually claim a credit to offset the double hit. California offers the Other State Tax Credit for this purpose.6State of California Franchise Tax Board. Other State Tax Credit
Nonresidents filing the 540NR can claim this credit for income taxes paid to their state of residence, but only if that home state does not already give them a credit for taxes paid to California.7California Franchise Tax Board. 2025 Instructions for Schedule S Other State Tax Credit Only one state gives you the credit; if the home state already provides it, California will not duplicate it.
California has reciprocal arrangements with Arizona, Oregon, and Virginia that determine which state’s return carries the credit. If you live in one of those states and have California-sourced income, you claim the credit on your California nonresident return rather than on your home state return. To claim it, complete Schedule S and attach a copy of the tax return you filed with the other state to your 540NR.7California Franchise Tax Board. 2025 Instructions for Schedule S Other State Tax Credit The credit applies only to net income taxes and cannot offset California’s Alternative Minimum Tax.
Deadlines and Extensions
Form 540NR is due April 15, or the next business day when that date falls on a weekend or holiday.8State of California Franchise Tax Board. Franchise Tax Board E-File Calendars California grants every individual filer an automatic six-month extension to file, pushing the return deadline to October 15 with no application or paperwork required.9California Franchise Tax Board. Due Dates Personal
Here is the catch that trips up nonresidents: the extension covers filing, not paying. Any tax owed must still reach the FTB by April 15 to avoid penalties and interest.9California Franchise Tax Board. Due Dates Personal If you cannot file by April 15 but expect to owe, use Form FTB 3519 to send your estimated payment on time.10Taxes (taxes.ca.gov). Extension of Time to File for Individuals
Taxpayers outside the United States on April 15 get an additional two months, which stacks on top of the automatic extension to push the filing deadline to December 15. Write “Outside the USA on April 15” in red ink at the top of the return.10Taxes (taxes.ca.gov). Extension of Time to File for Individuals
Penalties If You Miss
Missing FTB deadlines gets expensive fast, and the filing and payment penalties stack.
The delinquent filing penalty is 5% of the unpaid tax for each month or partial month the return is late, capped at 25%. For balances of $540 or less, a minimum penalty applies: the lesser of $135 or 100% of the tax due.11State of California Franchise Tax Board. Common Penalties and Fees Fraudulent failure to file carries a 15% per month penalty, up to 75%.12State of California Franchise Tax Board. FTB Pub. 1024 Penalty Reference Chart
The late payment penalty is separate: 5% of the unpaid tax plus an additional 0.5% for every month the balance remains unpaid, up to a combined maximum of 25%.12State of California Franchise Tax Board. FTB Pub. 1024 Penalty Reference Chart Interest accrues on top of both. The FTB’s personal income tax underpayment interest rate is 7% for the period through at least June 30, 2026.13State of California Franchise Tax Board. Interest and Estimate Penalty Rates
California does offer a one-time penalty abatement for individuals with an otherwise clean compliance history, available for tax years beginning on or after January 1, 2022.12State of California Franchise Tax Board. FTB Pub. 1024 Penalty Reference Chart If you have a genuine reason for the delay, you can also request a reasonable-cause waiver.
Estimated Tax Payments for Nonresidents
If you expect to owe California at least $500 after withholding and credits ($250 if married filing separately), you generally need to make quarterly estimated payments.14California Franchise Tax Board. 2025 Instructions for Form 540-ES Estimated Tax for Individuals Due dates are April 15, June 15, September 15, and January 15 of the following year.
A useful exception for people new to California taxation: if you had no California tax liability in the prior year, you are not required to make estimated payments for the current year.14California Franchise Tax Board. 2025 Instructions for Form 540-ES Estimated Tax for Individuals Once you have a California filing history, standard safe harbor rules apply. You generally avoid the estimated tax penalty by paying 90% of your current-year tax or 100% of your prior-year California tax, whichever is smaller.
High earners face a stricter rule. If your California AGI is $1,000,000 or more ($500,000 if married filing separately), the prior-year safe harbor disappears, and you must base payments on current-year actual tax.15California Franchise Tax Board. 2024 Instructions for Form FTB 5805 Underpayment of Estimated Tax by Individuals and Fiduciaries If you underpay, the FTB calculates the penalty after you file and sends a bill. Paying within 15 days of that notice avoids additional interest.
How to File and Fix Mistakes
The FTB accepts Form 540NR electronically through approved tax software or its own online services. E-filing speeds up processing and refunds. Paper returns go to the FTB address in the form instructions.
Pay any balance due through Web Pay, electronic funds withdrawal during e-filing, or a mailed check or money order. Finish your federal return first (Form 1040, 1040-SR, or 1040-NR) because the 540NR starts from those numbers, and have all W-2s, 1099s, and K-1s on hand. Part-year residents should also note the exact dates they moved into or out of California.
If you find an error after filing, the fix depends on the tax year. For 2017 and later, you file a corrected Form 540NR along with Schedule X, which explains the changes and calculates any additional tax owed or refund due.16Franchise Tax Board. Correct an Income Tax Return Attach Schedule X behind the corrected 540NR along with any updated supporting documents.17California Franchise Tax Board. 2024 Instructions for Schedule X California Explanation of Amended Return Changes For tax years 2016 and earlier, you use Form 540X instead.