If you moved into or out of California during the year, you are a part-year resident for California tax purposes, and you file Form 540NR. California part-year resident tax works in two pieces: during the months you lived in California, the state taxes your worldwide income from every source; during the months you did not, it taxes only income with a California source. The date your residency changed drives everything, and the Franchise Tax Board puts the burden of proving that date on you.
The stakes are real. California’s top marginal rate reaches 13.3%, and a 1% Mental Health Services Tax surcharge sits on top of that for very high earners. Getting the change date wrong, or misapplying the sourcing rules to stock compensation or a home sale, can move tens of thousands of dollars from one column to another.
Who Counts as a Part-Year Resident
California recognizes three statuses. A Resident is someone present in the state for more than a temporary or transitory purpose, or someone domiciled in California but temporarily outside it. A Nonresident is anyone who fits neither description. A Part-Year Resident held resident status for part of the year and nonresident status for the rest.1Franchise Tax Board. FTB Publication 1031 Guidelines for Determining Resident Status
The word that trips people up is domicile. Your domicile is the one place you intend to make your permanent home. You can only have one at a time, and it stays with you until you actively replace it. Simply being absent from California does not change it. If you move away but keep behaving like someone who plans to return, the FTB will treat you as a full-year Resident and tax your worldwide income for the whole year.
Changing your domicile requires three things happening together: abandoning the prior domicile, physically moving to and residing in the new location, and demonstrating through your actions an intent to remain there permanently or indefinitely.1Franchise Tax Board. FTB Publication 1031 Guidelines for Determining Resident Status Announcing the move is not enough. The FTB looks at the totality of your conduct, and a single lingering California tie can sink an otherwise strong case.
Proving Your Change of Domicile
No single factor decides the question. The FTB weighs many strands together, and consistency across categories is what carries weight. The factors that come up repeatedly:
- Housing. Selling or ending the lease on your California home and buying or leasing in the new state. Keeping a California residence available for your use is a red flag, even if you label it an investment property.
- Family and belongings. Where your spouse, children, pets, and valuable personal property are located. Moving your family but leaving a vintage car collection in a California garage sends a mixed signal.
- Voter registration. Canceling in California and registering in the new state. This is one of the clearest declarations of intent.
- Driver’s license. Surrendering the California license and getting one in the new state. The date on the new license is strong evidence of your claimed change date.
- Financial accounts. Updating the primary address on bank and brokerage accounts, closing California safe deposit boxes, and moving your main banking relationship.
- Professional ties. Transferring professional licenses, changing a business’s registered address, or resigning from California-based professional organizations.
- Social connections. Memberships in religious institutions, clubs, and community organizations. Joining a church in Texas while still attending services in Los Angeles undercuts the story.
Keep the paperwork: utility shutoff confirmations, moving invoices, new-state vehicle registrations, and dated address-change correspondence. The FTB’s statute of limitations for examining your return is generally four years from the filing due date, and longer periods can apply when income omissions exceed 25% or abusive avoidance is involved, so many practitioners recommend holding records well past the four-year mark.2Franchise Tax Board. Keeping Your Tax Records
The Safe Harbor for Long Work-Related Absences
If you leave California under an employment-related contract and stay away for at least 546 consecutive days, you qualify for a bright-line safe harbor that treats you as a nonresident during the absence. Return visits cannot exceed 45 days in any taxable year covered by the contract, and if your intangible income (interest, dividends, capital gains) exceeds $200,000 in any year during the contract, the safe harbor is lost. The same is true if the FTB determines the principal purpose of the absence was tax avoidance.1Franchise Tax Board. FTB Publication 1031 Guidelines for Determining Resident Status A spouse or registered domestic partner qualifies too, provided they accompany you for the full 546 days. If you do not meet these conditions, you fall back to the facts-and-circumstances test above.
What California Taxes During Each Portion of the Year
As a part-year resident, you owe California tax on all worldwide income received while you were a resident and on California-sourced income received while you were a nonresident.3Franchise Tax Board. Part-Year Resident and Nonresident The sourcing rules differ by income type, and this is where the most expensive mistakes happen.
Wages
Wages are sourced to the state where you physically performed the work. If you moved to Nevada on June 1 and kept working remotely for a California employer, wages earned while you were physically in Nevada are Nevada-sourced, assuming your domicile actually changed. Wages earned while you were physically in California, even after the move, remain California-sourced. A daily proration based on workdays in each state is the typical method for allocating pay that straddles the transition.
Capital Gains
Gains from real estate and tangible personal property are sourced to where the property is located. Sell a California rental after moving to Washington and the gain is still California-sourced.
Gains on intangibles like stocks and bonds generally follow your domicile at the time of the sale. Sell your portfolio after establishing domicile elsewhere, and the gain is typically sourced to the new state. Timing matters intensely. Selling appreciated stock the day before the domicile change means California taxes the whole gain; selling the day after generally does not. The FTB knows people try to time large sales around a move and scrutinizes suspiciously timed liquidations closely.
RSUs and Stock Options
Equity compensation is where sourcing catches tech workers off guard. California does not simply look at where you were when RSUs vested or when you exercised options. It allocates the income across the entire service period.
For restricted stock units, the FTB uses the ratio of California workdays to total workdays from grant to vest. If you worked in California for three of the four years between grant and vest, roughly 75% of the income recognized at vesting is California-sourced, even if you had already left the state by the vest date.4Franchise Tax Board. Residency and Sourcing Technical Manual
Nonstatutory stock options follow the same logic, using the grant-to-exercise period. If you were granted options while working in San Francisco and exercise them two years later from Seattle, California will tax the portion tied to your California service period.5Franchise Tax Board. Publication 1004 Equity-Based Compensation Guidelines
Retirement Income
Federal law bars states from taxing the retirement income of former residents. Distributions from 401(k)s, IRAs, pensions, 403(b)s, and government retirement plans are sourced to your state of residence when you receive them, not to the state where you earned the benefits.6Office of the Law Revision Counsel. 4 USC 114 – Limitation on State Income Taxation of Certain Pension Income Retire and leave California before taking distributions and California cannot tax them. Nonqualified deferred compensation may be treated differently depending on the plan’s terms and where the underlying services were performed.
Business Income
Income from a business operating both inside and outside California must be apportioned. Most businesses use a single-sales-factor formula, applying the ratio of California sales to total sales.7Franchise Tax Board. 2025 Instructions for Schedule R Certain qualified activities still use a three-factor formula that includes property and payroll.
Deductions and Credits
After you source your income, you prorate the rest. Itemized deductions like medical expenses or mortgage interest are allowed only in proportion to your California income relative to your total income, and tax credits are prorated using the ratio of California taxable income to total taxable income.
Items Part-Year Filers Often Miss
The 1% Mental Health Services Tax
California adds a 1% surcharge on taxable income over $1 million. The tax uses the same effective-rate approach as the rest of Form 540NR: worldwide income determines the rate, but only the California-sourced portion is actually taxed.8California Legislative Information. California Revenue and Taxation Code 17041 A part-year resident with a big income year can cross the $1 million threshold on worldwide numbers and pay the surcharge on the California slice even after just a few months in the state.
Community Property for Mixed-Residency Couples
If one spouse is a California resident and the other is not, community property rules can pull income across the line. Compensation earned by either spouse while domiciled in California is community income, meaning each spouse is treated as earning half. When a resident spouse and nonresident spouse file jointly, they use Form 540NR; when filing separately, each spouse reports half of all community income plus their own separate income.1Franchise Tax Board. FTB Publication 1031 Guidelines for Determining Resident Status The default 50/50 split can pull income into California that one spouse assumed was exempt, so couples with staggered move dates or different states of residence should work through the allocation carefully.
The California Moving Expense Deduction
Federal law suspended the moving expense deduction for most taxpayers through 2025, but California still allows it. If the move meets a distance test (your new workplace is at least 50 miles farther from your old home than your old workplace was) and a time test (you work full time in the new area for at least 39 weeks during the first 12 months), you can deduct qualified moving expenses on Form FTB 3913.9Franchise Tax Board. Instructions for Form FTB 3913 Moving Expense Deduction Active-duty military members moving on a permanent change of station are exempt from both tests. Qualifying costs include transporting household goods and personal effects and traveling to the new home.
Selling the California Home
Federal Section 121 lets you exclude up to $250,000 of gain ($500,000 for joint filers) on the sale of your principal residence if you owned and used it as your principal residence for at least two of the five years before the sale. If you fall short of the two-year use requirement because of a change in place of employment, health reasons, or certain unforeseen circumstances, you may still claim a prorated exclusion based on the fraction of the two-year period you met.10Office of the Law Revision Counsel. 26 USC 121 – Exclusion of Gain From Sale of Principal Residence Any gain above the exclusion is California-sourced because the property sits in California, whether or not you had already changed your domicile by closing.
Filing Form 540NR
Part-year residents file Form 540NR, the California Nonresident or Part-Year Resident Income Tax Return.11Franchise Tax Board. What Form You Should File The core of the return is Schedule CA (540NR), a five-column schedule that translates your federal return into California’s format.12Franchise Tax Board. 2024 Instructions for Schedule CA (540NR) California Adjustments – Nonresidents or Part-Year Residents Column A carries the federal amounts from Form 1040. Columns B and C hold subtractions and additions for differences between federal and California law, such as California lottery winnings (exempt) or out-of-state municipal bond interest (taxable in California). Column D is the combined result, treating you as a full-year California resident under California law. Column E is the number that actually drives your liability: income earned while a California resident, plus California-sourced income earned as a nonresident.
The tax itself uses an effective-rate method. California first computes the tax on your total taxable income (worldwide) using its regular tables. It divides that tax by total taxable income to produce an effective rate. Your California tax is your California taxable income multiplied by that rate.13Franchise Tax Board. 2025 540NR Booklet The effect is that you pay at the bracket your full income places you in, but only on the California portion. Someone with $300,000 of worldwide income and $100,000 of California income pays at the $300,000 rate on the $100,000 slice.
You can file electronically through approved software or by mail. California grants an automatic extension to October 15 to file, but any tax owed is still due by April 15 to avoid penalties.14Franchise Tax Board. Due Dates – Personal You do not attach your residency-change evidence to the return, but keep it organized in case the FTB asks.
Penalties and Interest If You Get It Wrong
Late filing carries a penalty of 5% of the unpaid tax for each month or partial month the return is overdue, capped at 25%. If the balance due is $540 or less, the penalty is the lesser of $135 or the amount owed.15Franchise Tax Board. Common Penalties and Fees
Late payment triggers a separate 5% underpayment penalty plus 0.5% for each additional month the balance is unpaid, up to 40 months.15Franchise Tax Board. Common Penalties and Fees The late-filing and late-payment penalties stack.
Interest accrues on unpaid tax from the original due date. The FTB’s interest rate on personal income tax underpayments is 7% for the period running from July 2025 through June 2026, and it keeps accruing until the balance is paid.16Franchise Tax Board. Interest and Estimate Penalty Rates For a part-year resident who miscalculated the change date and owes an additional $50,000, combined penalties and interest can add thousands within the first year alone.