Mental Incapacity and Changing Domicile

Barry received a call from his daughter, frantic. Her father, Barry, had suffered a stroke, and while recovering, a long-lost cousin convinced him to sign a new will, leaving everything to a charity Barry had never supported. The problem? Barry was heavily medicated, and his daughter suspects he lacked the capacity to understand what he was signing. Now, she’s facing a legal battle not only to challenge the will but also to determine if her father even intended to change his domicile to Nevada in the weeks leading up to the stroke – a move that could significantly impact California estate taxes. The potential cost of failing to properly address both issues? Hundreds of thousands of dollars, and a fractured family.

As an Estate Planning Attorney and CPA with over 35 years of experience, I’ve seen this scenario play out far too many times. The intersection of mental capacity, domicile, and estate planning is a complex legal landscape, and it requires careful navigation. Let’s break down the critical issues and how to protect your clients—or yourselves—from similar pitfalls.

What Constitutes Mental Incapacity in Estate Planning?

The legal standard for testamentary capacity—the ability to make a valid will—isn’t about being perfectly lucid. It’s a surprisingly low bar. Your client need only understand the nature of the act (making a will), the extent of their property, and who their natural heirs are. Even with cognitive decline, someone can meet this standard, making challenges difficult. However, if someone is under the influence of medication, experiencing a delirium, or suffers from a condition like severe dementia that impairs their understanding at the time of signing, that will can be invalidated.

Evidence is key here. Medical records documenting the stroke, medication list, and physician’s assessment of Barry’s cognitive state are crucial. Witness testimony from anyone who interacted with Barry around the time of the will signing—his daughter, nurses, even the cousin—can be invaluable. A subsequent capacity declaration from a qualified physician, assessing Barry’s condition after the signing, can also bolster a claim, although it’s not definitive.

How Does Domicile Factor Into Estate Planning?

Domicile is more than just a mailing address; it’s your true, fixed, permanent home, where you intend to return even if temporarily absent. This is where things get tricky, especially when someone is ill and potentially vulnerable. Changing domicile has significant tax implications, as California is known for its relatively high estate tax exposure, even after the One Big Beautiful Bill Act (OBBBA) permanently increased the Federal Estate Tax Exemption to $15 million per person effective Jan 1, 2026.

In Barry’s case, his daughter suspects a move to Nevada was orchestrated while he was incapacitated, potentially to shield assets from California estate tax. Establishing domicile requires looking beyond surface-level actions. Did Barry sever ties with California? Did he transfer bank accounts, register to vote, obtain a driver’s license, or change his primary medical providers to Nevada? Simply spending less than 183 days in California does not automatically terminate residency; the FTB uses the ‘Closest Connection’ test (evaluating 19 factors like your primary doctor and social ties) to determine domicile.

What About Challenging a Codicil or New Will?

A codicil, or a new will, can be challenged on several grounds: lack of testamentary capacity, undue influence, or fraud. Undue influence occurs when someone exerts such control over the testator (the person making the will) that the will reflects the influencer’s wishes, not the testator’s. The fact that the cousin suddenly appeared and convinced Barry to change his will while he was vulnerable raises a red flag.

Proving undue influence requires demonstrating a confidential relationship, susceptibility of the testator, active procurement by the influencer, and a result that appears unnatural. The timing, combined with Barry’s medical condition, strongly suggests undue influence.

What Role Does a CPA Play in These Complex Situations?

As a CPA as well as an attorney, I can’t stress enough the importance of understanding the tax implications of estate planning decisions. Moving assets, changing domicile, and establishing trusts all have potential tax consequences, particularly related to capital gains and the crucial concept of “step-up” in basis. A step-up in basis allows heirs to receive assets at their fair market value on the date of death, potentially eliminating years of accumulated capital gains tax. Understanding this, and the proper valuation of assets, is where a CPA’s expertise is invaluable.

Furthermore, when dealing with real property, it’s crucial to distinguish between the Small Estate Affidavit (strictly for real property <$69,625, used for timeshares/vacant land) and AB 2016. For deaths on or after April 1, 2025, a primary residence valued up to $750,000 qualifies for a 'Petition for Succession' under AB 2016 (Probate Code § 13151). Remember, this is a "Petition" that requires a Judge's Order, NOT an "Affidavit." It's also critical to clarify that to qualify, the decedent's other non-real estate assets (cash, stocks, etc.) must typically remain below the separate $208,850 Small Estate limit.

How do probate courts in California evaluate intent when a will is challenged?

In California, a last will and testament is reviewed under probate standards that focus on intent, capacity, and execution. Clear drafting reduces ambiguity, limits misinterpretation, and helps families avoid unnecessary conflict during estate administration.

To ensure the will functions as intended, the executor must understand their executor duties, while the family should be prepared for the court supervision required to enforce the document.

When a will is drafted with California probate review in mind, it becomes a stabilizing roadmap rather than a source of conflict. Clear intent, proper authority, and compliant execution protect both families and estates.

Controlling Legal Standards for Establishing Domicile and Residency

• Residency Guidelines: FTB Pub 1031 (Guidelines for Determining Resident Status)
  This is the primary resource for the “Closest Connection” test. In 2026, it details how the FTB evaluates 19 factors—including the location of your healthcare providers and social ties—to determine if your presence in the state is “permanent” or merely “transitory.”
• Voter Registration: California Secretary of State – Voter Registration
  Updating your voting address is a critical indicator of intent. For the June 2, 2026, Primary Election, the deadline to register online is May 18, 2026. This serves as a public declaration of your primary home.
• Federal Estate Tax: IRS Estate Tax Overview
  While domicile determines state tax, this resource outlines federal guidelines. It reflects the 2026 OBBBA update, which permanently set the federal estate tax exemption at $15 million per person ($30 million for couples), indexed for inflation.
• Proof of Residency: California DMV – REAL ID Checklist
  Since the federal enforcement deadline passed in 2025, a REAL ID is mandatory for domestic flights. This page lists the specific residency documents (e.g., utility bills, tax returns) that the state accepts as proof of a permanent California address.