7 Common Reasons Wills Are Invalid and How to Avoid Them

Quick answer: A California will can be thrown out for several reasons: the person who signed it lacked mental capacity, it was not signed and witnessed correctly under Probate Code section 6110, someone used undue influence or fraud to get it signed (Prob. Code section 6104), or it was revoked by a later document or act. Holographic (handwritten) wills have their own rules under section 6111. Any of these problems can send the estate into intestate succession, meaning California decides who gets what, not you.

Most people who come to Ridley Law after a loved one dies are not prepared for what they hear next: the will may not hold up. The problem is rarely dramatic, but the consequences are. A document signed in front of only one witness, or a relative who pressured grandma into changing her estate plan at the end of her life, can unravel years of planning. Eric D. Ridley has been helping Ventura County families with wills and estate planning since 2010, and the patterns he sees are consistent. Below are the seven most common reasons a California will gets declared invalid, grounded in actual California law.

1. Improper Execution: No Two Witnesses, No Valid Will

California Probate Code section 6110 sets the baseline rules for a written will. The document must be signed by the testator (the person making the will). It must also be signed, during the testator’s lifetime, by at least two witnesses who: (1) were present at the same time when the testator either signed the will or acknowledged the signature, and (2) understood that the instrument they were signing was the testator’s will.

That second requirement trips people up. A witness who thinks they are just signing a general document, and does not understand it is a will, does not count. And both witnesses must be there together, not on separate occasions.

Section 6110 does include a harmless error rule: if execution technically failed but clear and convincing evidence shows the testator intended the document to be their will, a court can still admit it. But do not count on that. A will drawn up and signed correctly is far more likely to hold.

2. Lack of Testamentary Capacity

To make a valid will in California, the testator must be at least 18 years old and of “sound mind.” Sound mind under California law means the person understood: (1) the nature of the act they were performing, (2) the general nature and extent of their property, (3) who their natural heirs are, and (4) how those things relate to each other to form a coherent plan of disposition.

Cognitive decline, advanced dementia, or a severe psychiatric episode at the time of signing can all support a capacity challenge. The key word is “at the time.” Someone with early dementia who has good days and bad days may have had capacity on the specific afternoon they signed the will. That is why documenting the signing, having a physician’s note from around that date, and working with an attorney who can attest to the person’s coherence, all help protect the will from later attack.

3. Undue Influence

California Probate Code section 6104 states that the execution of a will is ineffective to the extent it was procured by duress, menace, fraud, or undue influence. Undue influence means someone substituted their wishes for the testator’s genuine intent by using a position of power, trust, or dependence to overcome the testator’s free will.

It does not require physical force. An adult child who controls an elderly parent’s access to transportation, finances, and medical care, and who suddenly appears in the parent’s will for the first time, may have exerted undue influence even if no threat was ever made. Courts look at the totality of the relationship. Red flags include: isolation of the testator, a sudden change in the will that benefits someone in a caretaking role, and a testator who was already fragile or dependent.

The best protection is having an attorney meet one-on-one with the testator, without family members present, to confirm the plan reflects the person’s own wishes.

4. Fraud or Forgery

Fraud covers situations where someone deceives the testator into signing a will under false pretenses, for example, telling the person they are signing a power of attorney when the document is actually a will, or misrepresenting what the will contains. Forgery is the extreme end: fabricating the testator’s signature entirely.

Both fall under section 6104 and can void the affected provisions or the entire will. Courts take fraud and forgery seriously because they corrupt the very purpose of the document. If fraud is suspected, probate litigation typically involves handwriting experts, medical records, and testimony from people who knew the testator’s state of mind in the period before signing.

5. Revocation of the Will

A will is not permanent. California law allows a testator to revoke a will at any time before death by: (1) executing a new will that expressly revokes the prior one, (2) physically destroying the document with the intent to revoke it, or (3) certain changes in family status, such as a marriage after the will was signed.

Problems arise in a few common ways. First, someone makes a new will but forgets to include a clause revoking the prior one. Now two wills exist and a probate court has to figure out which provisions control. Second, someone tears up one copy of a will but other copies still exist. Under California law, if the testator destroyed one copy intending to revoke, the revocation may apply even to surviving copies, but this can be disputed. Third, a will signed before marriage may be partially or fully affected by the marriage under California’s rules on pretermitted spouses.

The cleanest approach: any new will should include a clear revocation clause stating that all prior wills and codicils are revoked, and old copies should be destroyed.

6. Holographic Will Problems

California is one of the states that allows holographic wills, meaning a will entirely in the testator’s own handwriting, signed by the testator, with no witnesses required. Probate Code section 6111 governs these.

The material provisions of a holographic will and the testator’s signature must all be in the testator’s own handwriting. That sounds simple, but it causes problems. A person who writes out a will on pre-printed stationery or a store-bought will kit may end up with a document where portions are printed rather than handwritten. If those printed portions contain material provisions, the will can fail entirely, or courts can end up ignoring the printed parts and trying to apply only what is handwritten, which may not reflect the full intent.

Date matters too. Section 6111 says that if there is doubt about which of two inconsistent wills controls, the holographic will is invalid to the extent of the inconsistency unless its execution date is established as later than the other will. An undated holographic will can create real problems.

7. Failure to Update After Major Life Changes

A will that was valid when signed can become a practical problem if it was never updated after significant life events. This is not technically a ground for “invalidity” the way improper execution is, but the consequences can be nearly as bad.

California law has specific rules on omitted spouses and omitted children. If you marry after making a will and fail to update it, your new spouse may be entitled to an intestate share of the estate under Probate Code section 21610 regardless of what the will says. If you have a child born or adopted after the will was signed and the child is not provided for, the child may be entitled to an intestate share under section 21620. An ex-spouse named as a beneficiary may lose their gift automatically on divorce under section 6122, but other provisions naming ex-family members do not have the same automatic cleanup.

The practical advice: review your will any time there is a marriage, divorce, birth, adoption, or death of a named beneficiary or executor. Every three to five years is a reasonable default interval even without a triggering event.

What Happens When a Will Is Declared Invalid?

If the entire will is thrown out and the person had no prior valid will, California’s intestate succession laws take over. That means the state’s formula distributes the estate, starting with the spouse and children, without any regard for what the person actually wanted. Assets intended for a close friend, a charity, or a non-biological family member go nowhere. The probate process typically takes longer and costs more. And family relationships can take serious damage.

Partial invalidity is also possible. A court may strike an individual provision, a gift to a specific person, or terms procured by undue influence while leaving the rest of the will intact. The outcome depends on the specific defect and whether it can be severed from the rest of the document.

For anyone in Ventura County who is concerned about whether an existing will is legally sound, or who needs to create or update one, Ridley Law offers a free initial consultation. Call (805) 244-5291 or visit the estate planning page to get started.

If a loved one has already died and you are questioning the validity of their will, the probate page explains how contested estate proceedings work in California. And if you are ready to take a closer look at your own plan, the wills attorney page walks through what the process looks like at Ridley Law.

Frequently Asked Questions

Does a California will need to be notarized to be valid?

No. California does not require notarization for a standard witnessed will to be valid. The requirements under Probate Code section 6110 are: the will must be in writing, signed by the testator, and signed by at least two witnesses who were present together and understood the document was a will. A notarized but unwitnessed will would still fail. That said, a self-proving affidavit, which does involve a notary, can simplify probate by reducing the need to locate witnesses later.

Can a will be challenged after probate is opened?

Yes, though timing matters. In California, a will contest must generally be filed before the court enters an order admitting the will to probate, or within the period set by the court’s notice. Once the court has admitted the will and the estate is distributed, overturning it becomes significantly harder. Anyone who suspects a will is invalid should consult an attorney quickly after the person’s death.

What makes a handwritten will valid in California?

A holographic will under Probate Code section 6111 is valid if the testator’s signature and all material provisions are in the testator’s own handwriting. No witnesses are needed. The main failure points are: using a pre-printed form where portions of the material terms are not handwritten, failing to date the document, and leaving out key provisions because the writer assumed too much would be understood from context. A simple handwritten document that clearly identifies what the person owns and who should receive it, signed and dated in the testator’s own hand, can be a valid will in California, but the margin for error is smaller than most people realize.

Can undue influence invalidate only part of a will?

Yes. Probate Code section 6104 says the will is ineffective “to the extent” it was procured by undue influence, duress, menace, or fraud. A court can strike a specific gift or bequest that was the product of manipulation while leaving the rest of the document intact, if the invalid portion can be severed. Whether the whole will fails or just the affected parts depends on whether the tainted provisions are so central to the document’s overall plan that removing them makes the rest incoherent.