What is an AB Trust?

AB Trust DefinitionAB Trust Definition

Key Takeaways

  • AB Trusts help married couples minimize estate taxes.
  • They split into two trusts (Trust A & Trust B) upon the first spouse's death, maximizing tax exemptions.
  • AB Trusts offer flexibility for the surviving spouse while preserving assets for heirs.
  • Complexity and irrevocability are key considerations when choosing an AB Trust.
  • Current estate tax laws may make AB Trusts less necessary for some couples.

How Does an AB Trust Work?

Here’s a step-by-step breakdown of how AB Trusts typically function:

Step 1: Establishing the Trust

  • Creation: Both spouses set up the joint AB Trust, usually as part of their broader estate planning. They transfer ownership of their assets—such as real estate, investments, and personal property—into the joint trust.
  • Ownership: The trust holds these assets on behalf of the spouses. Both spouses are typically the trustees, which means they manage the trust's assets together during their lifetimes.

Step 2: First Spouse's Death

Upon the death of the first spouse, the trust splits into two separate trusts: Trust A and Trust B.

  • Trust A (Survivor's Trust): This part of the trust generally holds assets up to the amount of the applicable estate tax exemption. It remains revocable, meaning the surviving spouse can alter its terms and has full control over the assets, including the right to spend the money or change beneficiaries.

    Note: Assets transferred into Trust A fall under the estate tax marital exemption, an unlimited marital deduction that covers any asset transfers made to a spouse before or after death. This provision in the U.S. tax code enables a married individual to pass on an unlimited number of assets to their surviving spouse without facing any federal estate or gift tax obligations.
  • Trust B (Bypass Trust or Family Trust): This trust is funded with assets up to the deceased spouse’s remaining estate tax exemption amount. It becomes irrevocable, meaning its terms cannot be altered after the death of the first spouse. The surviving spouse often has limited access to these funds, typically for health, education, maintenance, and support needs, ensuring the principal is preserved for future beneficiaries.

Step 3: Management During the Surviving Spouse’s Lifetime

  • Access to Assets: The surviving spouse can use the income generated by both trusts. However, their access to the principal may vary, especially with Trust B, which is usually more restricted to preserve it for other beneficiaries.
  • Flexibility and Control: Trust A provides the surviving spouse with significant flexibility, including the potential to alter beneficiaries. Trust B, while restrictive, ensures that the assets are eventually distributed according to the deceased spouse's original intentions.

Step 4: Upon the Death of the Surviving Spouse

  • Distribution of Assets: The assets in Trust A are handled according to the wishes of the surviving spouse, possibly going to their children, new spouse, or other designated beneficiaries. Trust B is distributed to its beneficiaries (e.g., children from the marriage) as originally specified by the first spouse who died.

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Pros: What are the Benefits of an AB Trust?

An AB Trust offers several benefits, particularly in the context of estate planning and asset management for married couples. Here are the key advantages:

Estate Tax Reduction

An AB Trust is designed to maximize the estate tax exemptions for both spouses. Upon the death of the first spouse, the estate is split into two trusts, and each spouse's estate can use up to their lifetime federal tax exemption (the current exemption in 2024 is $13.61M). This can significantly reduce the amount of estate tax payable when the second spouse dies, as assets in the Bypass Trust (irrevocable Trust B) are not included in the surviving spouse’s taxable estate.

Asset Protection

Assets placed in the Bypass Trust (Trust B) are generally shielded from creditors and legal claims against the surviving spouse. This protection remains intact even if the surviving spouse remarries, ensuring that the assets are preserved for the trust beneficiary designated by the first spouse to die.

Preservation of Assets for Future Generations

The AB Trust helps ensure that assets are preserved and passed on to future generations according to the wishes of the deceased spouse. This is particularly important in blended families, where a spouse may want to provide for their current spouse during their lifetime but ensure that the bulk of their estate ultimately goes to their own children from previous relationships.

Flexibility for the Surviving Spouse

Trust A (Survivor’s Trust) remains revocable, giving the surviving spouse flexibility to manage, use, and even modify the trust during their lifetime. This provides a balance between asset protection and access to resources, allowing the surviving spouse to adapt to changing financial needs or circumstances.

Maintaining Income for Surviving Spouse

The surviving spouse can receive income from both Trust A and Trust B, which can be crucial for maintaining their standard of living. Trust B can also provide principal amounts under certain conditions, such as health emergencies, educational needs, or maintenance, offering additional financial security.

Control Over the Distribution of Assets

The AB Trust structure allows each spouse to control the distribution of their portion of the estate. This control is particularly valuable in planning how heirs receive their inheritance, often facilitating smoother transitions and reducing potential conflicts among beneficiaries.


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 can be a vital component of long-term financial and estate planning, allowing couples to address not only their immediate concerns but also their extended outlook. It helps in setting up a structured approach to handle complex issues like taxes, remarriages, and blended family dynamics.

By integrating these features, an AB Trust can be a powerful tool for couples looking to optimize their estate planning, providing a strategic mix of tax efficiency, asset protection, and flexible control over their financial legacies.

Cons: What are the Drawbacks of an AB Trust?

While AB Trusts provide significant benefits in estate planning, there are also some drawbacks to consider. These potential disadvantages can affect whether an AB Trust is the right choice for particular situations:

Complexity and 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.


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 and 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.

When considering an AB Trust, it’s essential to weigh these potential drawbacks against the benefits and to discuss the options thoroughly with a qualified estate planner who can tailor advice to specific family circumstances and changing laws.

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 asset structures, or specific distribution requirements will naturally be more expensive due to the increased legal work involved.
  • Experience of the Attorney: Highly qualified estate planning attorneys in your area will likely charge higher fees than those with less experience.
  • Geographic Location: The cost of living and legal fees vary significantly between states and even cities. Expect higher rates in major metropolitan areas.
  • Attorney's Fee Structure: Some attorneys charge hourly rates, while others may offer flat-fee packages for standard trust creation.

Additional Costs to Consider:

  • Retitling Assets: Fees may apply for transferring assets (e.g., real estate, investment accounts) into the trust's name.
  • Ongoing Administration: If you hire a professional trustee, there will be annual fees associated with trust management.
  • Updating the Trust: If you want to make significant changes to your AB Trust over time, you may need legal assistance, which will incur additional fees.

When considering the establishment of an AB Trust, there are several legal considerations to keep in mind. These trusts, while offering significant benefits in estate planning, must be carefully structured to comply with legal standards. Here are some key legal considerations:

Compliance with State and Federal Laws

  • Estate and Gift Tax Laws: AB Trusts must be designed to take advantage of estate and gift tax exemptions under federal law, which often change. It's crucial to ensure that the trust adheres to the latest tax regulations to maximize these benefits.
  • State Trust Laws: Trust laws can vary significantly by state, especially concerning trust formation, administration, and termination. Local laws may also affect how trusts are taxed at the state level.

Funding the Trust

  • Proper Titling of Assets: Assets need to be correctly titled in the trust's name to ensure they are properly included and handled within the trust structure. This often involves transferring the titles of assets like real estate, accounts, and investments into the trust.
  • Consideration of Asset Types: Different asset types may have specific considerations. For example, the inclusion of retirement accounts like IRAs in an AB Trust can have significant tax implications and might require special 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 and 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

  • Optimization of 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 and Changes in Circumstances

  • Permanent Decisions: 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 and Probate Avoidance

  • Avoiding Probate: 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 and Family Dynamics

  • Addressing Potential Conflicts: 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 and Updates

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

These legal considerations are complex and require careful planning and professional advice. Engaging a knowledgeable estate planning attorney who understands both the nuances of AB Trusts and the specific legal landscape of your state is crucial to successfully implementing this estate planning strategy.

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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:

AB vs Simple vs QTIP Trusts TableAB vs Simple vs QTIP Trusts Table

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 might be a good fit for you if several key factors apply to your situation:

Do you meet the following criteria?

  • Married Couple: AB Trusts are specifically designed for married couples.
  • Sizeable Estate: If your combined estate value exceeds the current federal estate tax exemption ($13.61M in 2024), then tax savings become a significant consideration.
  • Tax Minimization Goal: Minimizing estate taxes for your heirs is a top priority in your estate planning strategy.

Here are some 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 potential limitations (e.g., reduced control over some assets) before proceeding.
  • Legal and Administrative Costs: Setting up and maintaining an AB Trust involves legal fees and potentially ongoing administrative costs. Weigh these against the potential tax benefits.
  • Portability for Exemptions: Check your state's estate tax laws. Portability allows the surviving spouse to use any unused portion of the deceased spouse's exemption, potentially reducing the need for an AB Trust in some cases.

An AB Trust offers a valuable tax-saving strategy for married couples with sizable estates. While AB trusts can involve complexity, the potential benefits often outweigh the initial setup process.

If protecting your family's financial future and minimizing estate taxes are priorities, schedule a consultation with a qualified estate planning attorney to explore if an AB Trust is the right fit for your unique situation.

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Frequently Asked Questions

Can an AB trust be changed by the surviving spouse?

The surviving spouse can modify Trust A of an A-B Trust, which is revocable and allows for adjustments to beneficiaries, distributions, or the trust itself after the first spouse's death. Trust B, however, becomes an irrevocable trust upon the first spouse's death, meaning its terms, including beneficiaries and distributions, cannot be changed by the surviving spouse.

Are AB Trusts obsolete?

AB Trusts are not obsolete, but their utility has diminished for some due to changes in federal estate tax laws, specifically the significant increase in estate tax exemptions. They remain a valuable tool for couples with large estates who want to minimize estate taxes and ensure specific asset distribution, particularly in complex family situations such as blended families.

What are AB Trusts also called?

AB Trusts are also commonly referred to as "bypass trusts," "credit shelter trusts," or "marital bypass trusts." These terms highlight the trust's function of sheltering assets from estate taxes by utilizing both spouses' tax exemptions. The different names emphasize the trust’s role in bypassing the surviving spouse’s estate to benefit other heirs while still providing for the spouse's needs.


  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
  3. Estate Tax - Internal Revenue Service (IRS). https://www.irs.gov/businesses/small-businesses-self-employed/estate-tax

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