Written by Sam Brotman, J.D., LL.M. (Taxation), MBA — Managing Attorney, Brotman Law  ·  Updated June 2026

How Many Months Is 183 Days?

183 days = 26.1 weeks = approximately 6 months and 2 weeks.

That is the straight answer to a question a lot of people search for when they are trying to figure out whether they have cleared California’s residency threshold. Most people arrive at that number because California imposes income tax on residents at rates up to 13.3%, and the 183-day figure gets cited in general discussions about state residency.

Here is the issue: 183 days is not the controlling threshold for California. It appears in some other states’ residency rules. California’s own threshold — under Revenue and Taxation Code § 17016 — is 546 days over a consecutive two-year period for the safe harbor presumption, not 183 days in a single year. And even if you understand the 546-day rule, day count alone does not determine California residency. California’s test is domicile-based.

Why Day Count Alone Does Not Determine Residency

California taxes residents on worldwide income at rates up to 13.3% — and “resident” means more than just physical presence.

Under California law, a “resident” includes any individual who is domiciled in California. Domicile is defined in FTB Publication 1031 as your “principal place of abode to which you intend to return.” It is where your life is centered, not just where you sleep the most nights in a given year.

This means two things. First, you can spend fewer than 183 days in California — or even fewer than the 546-day safe harbor threshold — and still owe California income tax on all worldwide income if the FTB determines you remained domiciled in California. Second, if you genuinely changed your domicile to another state and can prove it, California cannot tax your non-California-source income even if you spent more time in California than you intended during a given year.

The 546-day safe harbor under R&TC § 17016 is a presumption, not a guarantee. A California domiciliary who is present outside California for at least 546 days during a consecutive two-year period is presumed to be a nonresident. The FTB can still challenge that presumption — and will, in high-income cases — if your closest connections remained in California.

The practical consequence: leaving California is a two-part task. You have to actually move — establish your life and domicile somewhere else — and you have to stay out. Changing your address while keeping your family, your home, and your professional and community life in California does not constitute a change of domicile.

The FTB’s 9 Domicile Factors

FTB Publication 1031 lists nine factors the FTB considers in determining where a taxpayer is domiciled. No single factor is controlling, but some carry more weight than others.

1. Amount of time spent in California. Time in California versus time outside California is always the starting point. The closer the count is to the safe harbor threshold, the more scrutiny every individual day receives.
2. Location of your spouse or registered domestic partner and children. Where your family is tends to dominate the domicile analysis. If your spouse and children remain in a California home, the FTB will argue your domicile never changed.
3. Location of your principal residence. Owning or renting a home in California — particularly if it remains your primary residence and is not rented at arms-length — is strong evidence of continued California domicile.
4. State in which you are registered to vote. Voter registration is a specific, documented act. Staying on the California voter rolls after a claimed move cuts against nonresident status.
5. State where you hold professional licenses. California bar membership, California medical license, California real estate license — these tie your professional identity to California.
6. State where you are registered to conduct business. If your business entity is registered in California and you are its registered agent, the FTB treats that as a California connection.
7. Location of transactions and investments you personally manage. Where you actually conduct investment and business management activity matters — not just where the entity is registered.
8. Membership in professional associations, clubs, and organizations. Club memberships, gym memberships, professional association memberships, and religious affiliations are all on the FTB’s list.
9. Charitable causes and community ties. Boards you serve on, nonprofits you are affiliated with, and community involvement in California versus the new state.

The FTB looks at all nine factors and builds a picture of where your life is actually centered. In high-income departure cases — particularly those timed near a business sale or liquidity event — the FTB is thorough.

The Practical Departure Checklist

A clean departure from California requires changing your closest connections — not just your mailing address. The items below are the specific acts the FTB looks for as evidence that a domicile change was genuine. Work through these systematically, and document the date each one is completed.

1. Obtain a driver’s license in the new state. Surrender your California license. The date on the new license is a documented act of establishing domicile.
2. Register to vote in the new state. Cancel your California voter registration. Voter registration is specifically listed in FTB Publication 1031. Check both — register in the new state and confirm cancellation of California registration.
3. Change your bank accounts’ primary address to the new state. Open accounts at a financial institution in the new state if possible. Your primary bank should reflect your new address in all records.
4. Obtain a new-state professional license or transfer your existing licenses. If you hold a California bar card, a California medical license, a California broker registration, or any other state-issued professional license, transfer or obtain the equivalent in the new state. Keeping only a California license after a claimed move is an FTB audit point.
5. Move your primary physician, dentist, and specialists to the new state. Healthcare providers are geographic. The FTB sometimes requests medical records to establish where the taxpayer was physically located on specific dates.
6. Move your club memberships, religious institution, and professional associations to the new state. Cancel California gym memberships, country club memberships, and professional association chapter memberships. Join the equivalent in the new state.
7. Sell the California home or rent it at arms-length fair market value. This is one of the most significant factors. If you retain the California home as a personal residence — or rent it to a family member at below-market rates — the FTB will treat it as evidence that California remains your domicile. A genuine arms-length rental at FMV is better than keeping it vacant.
8. Update your will, trust, and estate documents to reflect the new state of domicile. Have the documents re-executed or amended to reflect your new state as the governing law jurisdiction and your new address as your domicile.
9. File a part-year resident return (California Form 540NR) for the year of departure. This is the tax return you file for the year in which you moved. It covers the California income you earned through your last day of California residency. Filing this correctly — and accurately stating the departure date — establishes the record you will rely on if the FTB later audits that year.
10. Maintain a contemporaneous daily calendar showing where you sleep each night. This is the most practical advice I give to people who have left California and have significant income. Keep a log. Record where you slept each night, contemporaneously. Flight records, credit card transactions, and hotel receipts all corroborate this, but the calendar is the backbone of any day-count defense.

California-Source Income That Continues After You Leave

Leaving California does not eliminate California tax liability on income that has a California source. California taxes nonresidents on California-source income under R&TC § 17041.

After a genuine change of domicile, you will still owe California income tax on:

• Stock options and restricted stock units (RSUs) attributable to California work. California uses an apportionment formula based on how many days you worked in California during the vesting period. Options and RSUs that vested while you were a California resident continue to generate California-source income on exercise or settlement, even after you have moved.
• Deferred compensation attributable to California services. Same apportionment logic applies to deferred compensation arrangements. The portion attributable to California service years is California-source income regardless of where you live when it is paid.
• K-1 income from California partnerships and LLCs. Your share of income from a California partnership or LLC is California-source income to you as a nonresident partner or member.
• Income from California real property. Rental income, gain on sale, and other income from real property located in California is California-source income.
• California business income. If you remain actively involved in managing a California-based business, the FTB may treat that income as California-source even if you are now a nonresident.

If you have stock options from a California-based employer and you plan to exercise them after moving, the California tax exposure can be significant. An analysis of the California apportionment fraction before exercise is worth the time.

FTB Audit Triggers for Departures

The FTB’s residency audit program is not random — it is data-driven, and certain facts reliably trigger examination.

The most common triggers in departure-year residency audits:

• Large income in the year of departure. A taxpayer who earned $500,000 in prior years and reports $5 million in the year they “left” California will draw scrutiny. The FTB looks for departures engineered to avoid California tax on a specific income event.
• Departure immediately before a business sale, IPO, or liquidity event. The FTB is specifically trained on this pattern. If the sequence is move → IPO or move → close of sale, the FTB will examine whether the move was genuine or whether California domicile was maintained through the event date.
• California home retained without a bona fide arms-length rental. Keeping the California home vacant, or renting it to a family member, is a persistent domicile indicator. The FTB will argue the home was available as a personal residence.
• Spouse or family remaining in California. If your spouse and children continue living in a California home, remain enrolled in California schools, and maintain California as their center of life, the FTB’s position will be that your domicile never left. This is the single most common point of failure in departure cases for married taxpayers.
• California business interests maintained. Continuing to manage, control, or hold a significant interest in a California business after your claimed departure raises the question of whether California ever ceased to be the center of your business and financial life.

If any of these factors are present, the departure should be planned carefully and documented thoroughly. We have represented clients through FTB residency examinations where the year of departure was the only year at issue — and the potential tax, penalties, and interest on a single large income event made the planning question far more consequential than most clients expected when they moved.

If you are in the process of leaving California and have a liquidity event on the horizon, I am happy to talk through the timing and what a defensible departure looks like. For clients already in an FTB audit challenging their departure, see our page on California residency audit attorney services.