You Were Told the Trust Has to Be Split. What That Means for a Surviving Spouse in California

Someone has told you that your trust now has to be split into two trusts. Maybe the bank said it. Maybe an accountant did. Maybe you found the language yourself while looking for something else.

It is an unsettling thing to learn while you are already grieving, especially from a document you and your spouse signed years ago and probably have not thought about since.

You do not need to understand the whole structure right now. What matters first is what the trust requires, what choices may still be open, and what to do before anything is retitled.

On this page:

• Why the trust has to be divided
• What a bypass trust is
• What you can and cannot change
• What you are allowed to take from the bypass trust
• The tax problem, with an example
• Whether an old A-B split can be undone
• What to do before you retitle anything

Why does the trust have to be divided when one spouse dies?

The trust has to be divided because the document requires it.

Many trusts written in the 1990s and 2000s were built as an A-B trust, sometimes called a bypass trust or a credit shelter trust. That design divides the estate at the first spouse’s death, and in many older documents the division is required rather than optional.

It made sense when it was written. Back then the federal estate tax exemption was a small fraction of what it is today, and dividing the trust at the first death was how planners helped families reduce or avoid estate taxes. For most families now, that concern is much smaller or gone.

The law changed, but the language in your trust did not.

What is a bypass trust, and how is it different from the survivor’s trust?

After the division, most older plans leave you with two separate trusts.

• The survivor’s trust holds your share. You generally remain in control of it, and you can usually change it, spend from it, and decide who receives it when you die.
• The bypass trust holds the deceased spouse’s share. You may still benefit from those assets, but the trust generally becomes irrevocable at the first death, which means the terms are largely fixed. It has its own rules about what you can receive and where the money goes when you die.

Some plans divide into three, adding a marital trust or QTIP trust alongside the other two. Which structure applies to you is written in your document.

The practical difference is control. One side is still yours to direct. The other side is now governed by decisions you and your spouse made years ago.

What can I change, and what is now fixed?

This is the question surviving spouses ask us first, and the answer depends on the trust.

As a general matter, the survivor’s trust usually remains yours to amend. The bypass trust usually does not, because it generally became irrevocable when your spouse died.

That said, “irrevocable” is not always the end of the conversation. Some trusts build in their own flexibility, such as a power held by the surviving spouse or the trustee to make certain changes or distributions. And in some circumstances, California law provides ways to modify or terminate an irrevocable trust, though whether any of them are available depends on the trust’s terms and the specific facts.

What am I allowed to take out of the bypass trust?

The answer is also written in the trust, and it varies more than people expect.

Many bypass trusts allow the surviving spouse to receive income and to use principal for certain needs defined in the trust, often including health, education, maintenance, and support. Some are more flexible. Others give a trustee more control over when money can be distributed.

Two things are worth knowing before you take anything:

• Distributions from the bypass trust are usually governed by a standard, not by preference. Taking money outside what the trust allows can create real problems later, particularly if children or other beneficiaries eventually receive what is left.
• The bypass trust generally files its own tax return and is administered as its own entity, separate from your personal finances.

If you have already been taking distributions without knowing which trust they came from, say so early. It is a common situation and it is easier to address the sooner it is raised.

How does the split affect taxes for my children?

This is the part most families never hear about until much later.

When someone dies, the assets they owned generally get a fresh starting value for tax purposes, equal to what the asset is worth on the date of death. That reset is called a step-up in basis, and it can erase years of built-in gain, so there is often little or no capital gains tax if the asset is sold.

Assets in the bypass trust are generally outside your estate. That is what the structure was designed to do. But it means those assets often do not get a second step-up when you die. Any built-in gain that accumulates after the first death may remain taxable when your children later sell the asset.

Here is a simplified illustration. Say you and your spouse bought a rental property for $200,000 years ago, and it was worth $1 million when your spouse died. Half of it moved into the bypass trust with a fresh starting value of $500,000. Fifteen years later the property is worth $1.6 million.

At your death, the half in your survivor’s trust gets a fresh starting value again, so that growth generally escapes tax when the property is later sold. The half sitting in the bypass trust usually does not get another fresh starting value for tax purposes. Your children would generally owe capital gains tax on roughly $300,000 of gain on that side alone, when the property is sold.

This is an illustration, not a prediction about your trust. Whether it applies to you depends on how your trust was drafted, what was actually funded into each side, and what you own. It is worth finding out which side of that line your family is on while there are still choices to make.

Can an old A-B split be undone?

Sometimes the split can be changed, and sometimes it cannot. It depends on the trust and on how far along the administration is.

The most important thing to know is that the options are widest before anything is retitled. Once the division has been carried out and property has been retitled, the choices narrow, and unwinding what has already been done is harder than deciding carefully in the first place.

In some cases, once the structure is locked in at the first death, changing it may require a petition in probate court. That is a real process with real cost, and it is one of the reasons we encourage couples to review an old A-B trust while both spouses are still living, when a restatement can handle it privately.

Either way, the trust has to be read closely first. After a first spouse dies, that reading is necessary in every case, because what the trust requires and what choices are still open are both written in the document.

And if the split is going to stand, the work shifts to carrying it out correctly. The two trusts have to be funded the way the document requires, with assets valued as of the date of death and titled to the right side. Doing that carefully the first time is easier than correcting it later.

What should I do before I retitle anything?

1. Find the trust and read who is named. You need the original trust and any amendments. If your spouse handled the paperwork, this may take some looking, and that is normal.
2. Do not retitle accounts or property yet. Once assets are moved into the wrong trust, correcting it is more work than dividing them correctly the first time. This is one of the most common things we ask families to pause on.
3. Get the date-of-death values. Real estate, investment accounts, and business interests generally need to be valued as of the date your spouse died. Those numbers drive the division and the basis for everything after it.
4. Have the trust reviewed before you act on it. Some older structures still serve a family well. Others create work and tax cost that a current plan would have avoided. Which one yours is depends on how it was drafted and what you own, and there is no way to know without reading the document.

Your own plan will need attention too. The document that named your spouse as trustee, agent, and beneficiary generally needs to be brought current after their death, and that is usually part of the same conversation.

Where we come in

We handle the first death in an older A-B trust regularly as part of our trust administration work. We read the trust, explain what it requires and what options may be available, coordinate the division and the tax reporting with your accountant, and refresh your own plan once the administration is settled. If a court petition turns out to be the only way to fix a structure that no longer serves your family, we will tell you that plainly and what it would involve.

No one is expected to know any of this. Most people in your position are learning the term “bypass trust” for the first time.

If you have been told your trust has to be divided, you do not need to work out the structure on your own. The next step is having the trust read carefully, so you know what it requires, what choices may still be open, and what needs to happen next.

When you are ready, talk with us or call (949) 718-0420. We will read the trust with you, explain where things stand, and map the next steps.

Laura Meier, Esq., Founder, Meier Law Firm · Newport Beach, California · Last reviewed August 2026