If you moved into or out of California during the tax year, California’s part-year resident tax rules split your year into two periods: while you were a resident, California taxes your worldwide income from every source; while you were a nonresident, California taxes only income with a California source. You report both periods on a single return, Form 540NR, and the tax is calculated using an effective rate drawn from your full-year income. The date your residency actually changed drives everything, and the Franchise Tax Board puts the burden of proving that date on you.
Who Counts as a Part-Year Resident
California recognizes three statuses for income tax purposes: Resident, Nonresident, and Part-Year Resident. A Part-Year Resident is simply someone who 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 concept doing the real work here 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 with a new one. Physical absence from California alone does not change it. If you move to another state but keep acting like someone who plans to return, the FTB will treat you as a full-year Resident taxed on worldwide income.
Changing your domicile requires three things to happen together: you abandon your prior domicile, you physically move to the new location and reside there, and your actions show an intent to remain permanently or indefinitely.1Franchise Tax Board. FTB Publication 1031 Guidelines for Determining Resident Status Telling friends you’ve moved is not enough. The FTB looks at the full picture of your life, and a single lingering California tie can undermine an otherwise strong case.
Proving When Your Residency Changed
No single factor settles the question, but a consistent paper trail across several categories is the strongest defense. Inconsistencies kill credibility fast.
The factors the FTB weighs most heavily:
- 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 labeled as an investment property.
- Family and belongings. Where your spouse, children, pets, and valuable personal property actually are. Moving the family while leaving a vintage car collection in a California garage sends a mixed signal.
- Voter registration. Canceling California registration and registering in the new state is one of the clearest declarations of intent.
- Driver’s license. Surrendering your California license and getting one in the new state. The issue date is strong evidence of your claimed change date.
- Financial accounts. Updating the primary address on bank and investment accounts, closing California safe deposit boxes, and moving your main banking relationship.
- Professional ties. Transferring professional licenses, updating a business’s registered address, resigning from California-based professional organizations.
- Social connections. Memberships in religious institutions, country clubs, and community organizations. Joining a church in Texas while still attending services in Los Angeles is the kind of pattern the FTB notices.
Keep the documentation: utility shutoff confirmations, moving company invoices, new-state vehicle registrations, dated correspondence showing address changes. The FTB’s statute of limitations to examine your return is generally four years from the filing due date, so hold records at least that long. Extended limitation periods apply when income omissions exceed 25% or abusive tax avoidance is involved, so many practitioners keep records longer.2Franchise Tax Board. Keeping Your Tax Records
What California Can Tax After You Move
During your resident period, California taxes everything. During your nonresident period, California taxes only California-sourced income.3Franchise Tax Board. Part-Year Resident and Nonresident The sourcing rules vary by income type, and this is where expensive mistakes happen.
Wages and Service Income
Wages are sourced to the state where you physically performed the work. If you moved to Nevada on June 1 but kept working remotely for a California employer through year-end, wages earned while physically in Nevada are Nevada-sourced, not California-sourced, assuming your domicile had changed. Any days you physically worked inside California after the move remain California-sourced. A daily proration based on workdays in each state is the typical method for wages that straddle the transition.
Capital Gains
Gains from real estate or tangible personal property are sourced to where the property sits. Sell a California rental after moving to Washington, and the gain is still California-sourced.
Gains from intangibles like stocks and bonds generally follow your domicile on the sale date. Sell appreciated stock the day before your domicile change, and California taxes the full gain. Sell the day after, and the gain is generally sourced elsewhere. The FTB knows people try to time large sales around a move and scrutinizes transactions where the claimed change date lines up suspiciously with a major liquidation event.
Equity Compensation
Stock-based pay is where California’s rules surprise a lot of tech workers. The state doesn’t just look at where you were when shares vested or options were exercised. It allocates the income across the entire service period.
For restricted stock units, the FTB uses a ratio of California workdays to total workdays from the grant date to the vesting date. If you worked in California for three of the four years between grant and vest, roughly 75% of the vesting income is California-sourced, even if you were living elsewhere when the shares vested.4Franchise Tax Board. Residency and Sourcing Technical Manual
Nonstatutory stock options use the same logic from grant date to exercise date. California workdays during that window divided by total workdays sets the allocation. Options granted while you worked in San Francisco and exercised two years later from Seattle will still produce California tax on the portion tied to the 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) plans, IRAs, pensions, 403(b) plans, and government retirement plans are sourced to your state of residence when you receive them, not where you earned the underlying benefits.6Office of the Law Revision Counsel. 4 USC 114 – Limitation on State Income Taxation of Certain Pension Income If you leave California before taking distributions, California cannot tax those payments. Nonqualified deferred compensation can be treated differently depending on the plan’s terms and where the services were performed.
Business Income
Business income earned both inside and outside California is apportioned. Most businesses use a single-sales-factor formula: the ratio of California sales to total sales sets the percentage of business income California can tax.7Franchise Tax Board. 2025 Instructions for Schedule R
Selling the California Home
Many people sell their California home as part of the move. The federal exclusion under Section 121 lets you exclude up to $250,000 of gain, or $500,000 for married couples filing jointly, if you owned and used the home as your principal residence for at least two of the five years before the sale. If you haven’t met the full two years because you’re selling sooner than planned, a prorated exclusion may apply when the sale is tied to a change in place of employment, health reasons, or certain unforeseen circumstances.8Office 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, no matter where your domicile is when the deal closes.
How the Tax Is Calculated on Form 540NR
Part-year residents file Form 540NR, California Nonresident or Part-Year Resident Income Tax Return.9Franchise Tax Board. What Form You Should File The heart of it is Schedule CA (540NR), a five-column schedule that translates your federal return into California’s format.10Franchise Tax Board. 2024 Instructions for Schedule CA (540NR) California Adjustments – Nonresidents or Part-Year Residents The columns work this way:
- Column A holds your federal amounts, copied from Form 1040.
- Columns B and C hold subtractions and additions for differences between federal and California tax law, such as California lottery winnings (exempt) or out-of-state municipal bond interest (taxed by California).
- Column D is the combined result, your total income as if you were a full-year California resident under California law.
- Column E is the figure that actually matters for your bill: income earned while a California resident plus California-sourced income earned as a nonresident.
California then uses an effective-rate method. It calculates the tax on your total taxable income (worldwide) using its standard tables, divides that tax by your total taxable income to get an effective rate, and applies that rate to your California taxable income.11Franchise Tax Board. 2025 540NR Booklet You pay at the bracket your full income lands in, but only on the California portion. Someone with $300,000 worldwide income but only $100,000 during the resident period still pays at the rate corresponding to $300,000 of income on that $100,000.
After sourcing income, you prorate deductions. Itemized deductions like medical expenses or mortgage interest are allowed only in proportion to your California income relative to your total income. Tax credits are prorated the same way, using the ratio of California taxable income to total taxable income.
California also imposes an additional 1% Mental Health Services Tax on taxable income above $1 million.12California Legislative Information. California Revenue and Taxation Code 17041 For part-year residents, the surcharge rides on the same effective-rate mechanic: worldwide income determines whether the higher rate applies, and that rate then hits the California-sourced portion. A part-year resident with a big income year can get caught by this even after only a few months in the state.
California grants an automatic extension to October 15 to file, but any tax owed must still be paid by April 15 to avoid penalties.13Franchise Tax Board. Due Dates – Personal You do not submit your residency-change evidence with the return. Keep it organized in case the FTB asks later.
Married Couples and Community Property
When spouses have different residency statuses, California’s community property rules add a layer. Compensation earned by either spouse while domiciled in California is community income, meaning each spouse is treated as earning half. A resident spouse and nonresident spouse filing jointly use Form 540NR. When filing separately, each spouse reports half of all community income plus all of their own separate income.1Franchise Tax Board. FTB Publication 1031 Guidelines for Determining Resident Status The nonresident spouse may need to report a share of the resident spouse’s California-sourced earnings, and vice versa. Couples who split their move across different dates or who live in different states should work through the allocation carefully, because the default 50/50 split can pull income into California that one spouse assumed was exempt.
Moving Expense Deduction
Unlike federal rules, which suspended the moving expense deduction for most taxpayers through 2025, California still allows it. If your move meets both the distance test (your new workplace is at least 50 miles farther from your old home than your old workplace was) and the time test (you work full time in the new area for at least 39 weeks during the first 12 months after the move), you can deduct qualified moving expenses on Form FTB 3913.14Franchise Tax Board. Instructions for Form FTB 3913 Moving Expense Deduction Active-duty military members moving under a permanent change of station are exempt from both tests. Qualifying expenses include transporting household goods and personal effects along with travel to your new home.
Penalties and Interest for Getting It Wrong
The FTB does not take a light touch with part-year resident mistakes. Understate your California income by using the wrong change date or misapplying sourcing rules, and multiple charges stack up.
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 your balance due is $540 or less, the penalty is the lesser of $135 or the full amount owed.15Franchise Tax Board. Common Penalties and Fees
Late payment triggers a separate 5% underpayment penalty plus an additional 0.5% for each month the balance stays unpaid, up to 40 months.15Franchise Tax Board. Common Penalties and Fees These penalties layer on top of each other.
Interest runs on all unpaid tax from the original due date. The FTB’s interest rate on personal income tax underpayments is 7% for the period from July 2025 through June 2026.16Franchise Tax Board. Interest and Estimate Penalty Rates Interest is not capped and keeps running until the balance is paid. For a part-year resident who miscalculated the change date and owes an extra $50,000, combined penalty and interest exposure can add thousands of dollars in the first year alone.