What Is an AB Trust? How Do They Work?

How Does an AB Trust Work?

Here is a step-by-step breakdown of how AB trusts typically work.¹

Step 1: Establishing the Trust

• Creation: Both spouses create a joint AB trust, often as part of their broader estate planning. They transfer ownership of assets such as real estate, investments, and personal property into the trust.
• Ownership: The trust holds these assets for the spouses. Both spouses usually act as trustees, meaning they manage the trust together during their lifetimes.

Step 2: First Spouse's Death

When the first spouse dies, the trust splits into two separate trusts: Trust A and Trust B.²

Trust A (Survivor’s Trust)

This portion of the trust typically holds assets up to the estate tax exemption amount. It remains revocable, so the surviving spouse can change its terms and control the assets. This includes the ability to spend the money or update beneficiaries.

Note: Assets placed in Trust A qualify for the estate tax marital exemption. This allows a married person to transfer an unlimited amount of assets to a surviving spouse without federal estate or gift taxes.

Trust B (Bypass Trust or Family Trust)

This trust is funded with assets up to the deceased spouse’s remaining estate tax exemption. It becomes irrevocable after the first spouse’s death, so its terms cannot be changed. The surviving spouse may have limited access to these funds, usually for health, education, maintenance, and support. This structure helps preserve the assets for future beneficiaries.

Step 3: Management During the Surviving Spouse’s Lifetime

• Access to Assets: The surviving spouse can use income from both trusts. Access to the principal may be limited, especially for Trust B, to help preserve assets for other beneficiaries.
• Flexibility and Control: Trust A gives the surviving spouse more control, including the option to change beneficiaries. Trust B has more limits but helps make sure assets are distributed based on the first spouse’s wishes.

Step 4: Upon the Death of the Surviving Spouse

Assets in Trust A are distributed based on the surviving spouse’s wishes. These may go to children, a new spouse, or other beneficiaries. Trust B assets are distributed to the named beneficiaries, such as children, based on the original instructions set by the first spouse who died.

Pros: What Are the Benefits of an AB Trust?

An AB Trust offers several advantages for married couples managing their estate and assets.

Estate Tax Reduction

An AB Trust helps maximize estate tax exemptions for both spouses. When the first spouse dies, the estate is divided into two trusts. Each spouse can use their lifetime federal tax exemption (the current exemption in 2026 is $15M).²

Assets in the Bypass Trust (Trust B) are not included in the surviving spouse’s taxable estate, which can lower estate taxes after the second spouse dies.

Asset Protection

Assets placed in the Bypass Trust (Trust B) are generally protected from creditors and legal claims against the surviving spouse. This protection typically continues even if the surviving spouse remarries, helping preserve assets for the intended beneficiaries.

Preservation of Assets for Future Generations

An AB Trust helps carry out how assets are passed to future generations based on the deceased spouse’s wishes. This can be especially helpful for blended families. A spouse can support their partner during their lifetime while directing assets to their own children later.

Flexibility for the Surviving Spouse

Trust A (Survivor’s Trust) remains revocable. The surviving spouse can manage, use, or modify it as needed. This allows adjustments over time as financial needs or circumstances change.

Maintaining Income for Surviving Spouse

The surviving spouse can receive income from both Trust A and Trust B. Trust B may also provide access to principal in certain situations, such as health needs, education, or general support.

Control Over the Distribution of Assets

Each spouse can determine how their portion of the estate is distributed. This can help guide how heirs receive assets and may reduce conflicts among beneficiaries.

Privacy

Since the assets are handled within a trust, the details of the estate may not need to go through the public process of probate. This can offer privacy to the family regarding the assets and terms of the estate distribution.

Long-Term Planning

An AB Trust supports a structured approach to managing estates over time. It can address taxes, remarriage, and blended family considerations while helping organize how assets are handled across generations.

By integrating these features, an AB Trust combines tax advantages, asset protection, and control, making it a useful option for couples planning how their assets will be managed and distributed.

Cons: What Are the Drawbacks of an AB Trust?

While AB Trusts offer benefits, they also come with trade-offs. These drawbacks may affect whether this strategy fits your situation.

Complexity & Cost

Setting up and maintaining an AB Trust can be complex and typically requires the assistance of an experienced estate planning attorney. This complexity often leads to higher initial setup costs and ongoing administrative expenses, including the need for separate tax filings for the trusts after one spouse’s death.

Irrevocability

Once the first spouse passes away and Trust B (the Bypass Trust) is established, it becomes irrevocable. This means that no changes can be made to Trust B, which can be restrictive. The surviving spouse, despite having access to the income, may have limited access to the principal and cannot change the beneficiaries of Trust B.

Potential Overfunding

Given the increases in federal estate tax exemptions (significantly higher than in past decades), there is a potential risk of overfunding Trust B. This could unintentionally limit the surviving spouse's access to sufficient assets, especially if most of the couple's assets are directed into the Bypass Trust to minimize estate taxes.

Changes in Tax Laws

Estate planning strategies are often influenced by current tax laws, which can change. For example, recent increases in estate tax exemptions have made the tax-saving advantages of AB Trusts less significant for many families. Dependence on this form of trust might not provide the anticipated tax benefits if laws change after the trust is established.

Reduced Step-Up in Basis

Assets in Trust B do not receive a step-up in basis upon the death of the surviving spouse because they are not included in the surviving spouse's estate. This could result in higher capital gains taxes when the beneficiaries eventually sell these assets, as compared to assets transferred directly or held in a different type of trust that allows for a step-up in basis at each spouse’s death.

Potential Conflict Among Beneficiaries

The irrevocable nature of Trust B can lead to potential conflicts, especially in blended families. If the surviving spouse and the beneficiaries of Trust B (often children from a previous marriage) have different financial goals or needs, this can create tension and disagreements over the management and distribution of the trust assets.

Lack of Flexibility

The structured nature of an AB Trust can be a disadvantage if the surviving spouse's needs change significantly over time. Financial situations can evolve, and having a large portion of assets tied up in an irrevocable trust can restrict the surviving spouse’s ability to adapt to new circumstances.

Emotional & Psychological Impact

The process of dividing assets into separate trusts upon the death of a spouse can also have an emotional and psychological impact on the surviving spouse and other family members. It formalizes the separation of assets in a way that might not reflect the surviving spouse's wishes or the dynamic needs of their family.

Before moving forward, weigh these drawbacks alongside the benefits and review your options with a qualified estate planner.

How Much Does an AB Trust Cost?

Unfortunately, there's no single answer to how much an AB trust costs. The price will vary widely depending on several factors:

• Complexity of Your Situation: AB trusts for couples with large estates, complex assets, or detailed distribution instructions often cost more. This is because they require more time and legal work to set up.
• Experience of the Attorney: Estate planning attorneys with more experience or specialized knowledge may charge higher fees than those with less experience.
• Geographic Location: Costs can vary depending on where you live. Legal fees and the cost of living are often higher in large cities than in smaller towns.
• Attorney's Fee Structure: Some attorneys charge by the hour, while others offer flat fees for creating a trust. The total cost will depend on the structure they use.

Additional Costs to Consider

There are other expenses to keep in mind beyond the initial setup:

• Retitling Assets: You may need to pay fees to transfer assets, such as real estate or investment accounts, into the name of the trust.
• Ongoing Administration: If you choose a professional trustee, there may be yearly fees to manage the trust.
• Updating the Trust: If you decide to make major changes to your AB trust over time, you may need legal help, which can add to the cost.

Legal Considerations for AB Trust

Setting up an AB trust requires careful attention to legal details. These trusts can offer benefits, but they must follow current laws and be structured correctly.

Compliance with State & Federal Laws

• Estate and Gift Tax Laws: The trust should align with current federal tax rules and exemption limits, which may change over time.
• State Trust Laws: Rules vary by state and can affect how a trust is created, managed, and taxed.

Funding the Trust

• Proper Titling of Assets: Assets must be placed in the trust’s name. This may include real estate, bank accounts, and investments.
• Asset Type Considerations: Some assets, like IRAs, may involve added tax considerations and require additional planning.

Designation of Trustees

• Choice of Trustees: It is crucial to select a trustworthy and competent trustee, as this individual or institution will manage the trust assets upon the death of the first spouse. The trustee's responsibilities include managing assets, making distributions as per the trust terms, and handling tax matters.
• Successor Trustees: It’s important to designate successor trustees who can step in if the original trustee is unable to perform their duties.

Trust Terms & Conditions

• Specificity of Terms: The terms of both Trust A (Survivor's Trust) and Trust B (Bypass Trust) need to be clearly defined, including what happens upon the death of the first spouse, the rights and limitations of the surviving spouse, and the ultimate distribution of assets to beneficiaries.
• Flexibility for Changes: While Trust B becomes irrevocable upon the death of the first spouse, Trust A typically remains revocable. However, consideration should be given to the potential need for amending trust terms in response to changes in law or family circumstances during the surviving spouse’s lifetime.

Marital Deduction

Proper planning should ensure that the trust is structured to optimize the unlimited marital deduction available under U.S. tax law, which allows assets to pass to the surviving spouse without immediate estate tax consequences.

Irrevocability & Changes in Circumstances

Since Trust B becomes irrevocable, it is critical to consider long-term implications carefully. Conditions change, and what may seem like an ideal arrangement now might not suit the family's needs in the future.

Privacy & Probate Avoidance

By holding assets within a trust, the estate may avoid the probate process, which can save time and preserve privacy. However, the correct establishment and maintenance of the trust are key to achieving this benefit.

Potential Conflicts & Family Dynamics

Especially in families with complex dynamics or blended family structures, it's essential to anticipate potential conflicts and address them within the trust agreement to minimize disputes among beneficiaries.

Regular Reviews & Updates

Regular reviews of the trust documents with an attorney are necessary to help ensure that the trust continues to meet legal standards and family goals, especially as laws and personal circumstances change.

These considerations can be complex. Working with an estate planning attorney can help guide decisions and support proper setup based on current laws.

AB Trust vs. Simple Trust vs. QTIP Trust

When comparing an AB Trust, a Simple Trust, and a QTIP (Qualified Terminable Interest Property) Trust, it's essential to understand their key differences, here's a comparison of these three types of trusts:

Choosing between an AB Trust, a Simple Trust, and a QTIP Trust depends on your specific goals, family situation, and estate planning needs. If minimizing estate taxes is your primary objective, an AB Trust may be the most suitable option.

As with any estate planning decision, consult a qualified estate planning attorney to determine which trust structure best aligns with your unique circumstances and objectives.

Is an AB Trust Right for You?

An AB Trust may be a good fit if these factors apply to your situation.

Do You Meet These Criteria?

• Married Couple: AB Trusts are designed for married couples.
• Sizeable Estate: Your combined estate exceeds the federal estate tax exemption ($15M in 2026).²
• Tax Minimization Goal: Reducing estate taxes for your heirs is a priority.

Additional Factors to Consider

• Understanding Complexity: AB Trusts are more complex than simple wills or revocable living trusts. You should be comfortable with the structure and possible limitations, such as reduced control over some assets.
• Legal and Administrative Costs: Setting up and maintaining an AB Trust may involve legal fees and ongoing administrative costs. Compare these costs with potential tax savings.
• Portability for Exemptions: Review your state’s estate tax laws. Portability allows a surviving spouse to use any unused exemption, which may reduce the need for an AB Trust in some cases.

An AB Trust can help married couples with larger estates reduce estate taxes. While it adds complexity, the tax benefits may make it worth considering. If minimizing estate taxes is a priority, consider speaking with a qualified estate planning attorney to determine if an AB Trust fits your situation.

Final Thoughts

An AB Trust can help married couples manage how assets are protected, distributed, and potentially taxed over time. While it offers clear advantages for larger estates, it also comes with added complexity and ongoing responsibilities. Reviewing your goals with an estate planning attorney can help you decide if this approach aligns with your long-term plans.

Sources

1. AB Trust - Cornell Law School - Legal Information Institute. https://www.law.cornell.edu/wex/ab_trust.
2. Do You Still Need Your AB Trust? - Nolo. https://www.nolo.com/legal-encyclopedia/do-you-still-need-your-ab-trust.html.