Choosing between a QTIP trust and a bypass trust comes down to a single question: do you want to defer estate tax until the second spouse dies while preserving a fresh cost basis for your heirs, or do you want to move assets out of both spouses’ estates permanently? A Qualified Terminable Interest Property (QTIP) trust does the first. A bypass trust, also called a credit shelter trust, does the second. Both provide for a surviving spouse and control who inherits later, but they use the estate tax exemption at different times, protect against creditors to different degrees, and produce very different income tax outcomes for the people who eventually inherit.
The Core Tax Difference
A QTIP trust qualifies for the unlimited marital deduction. When the first spouse dies, no federal estate tax is owed on the assets placed in the trust. The surviving spouse must receive all trust income, paid at least annually, for life, and no one can direct the property to anyone else during that time.1Office of the Law Revision Counsel. 26 U.S. Code 2056 – Bequests, etc., to Surviving Spouse The executor of the deceased spouse’s estate makes an irrevocable QTIP election, and the deferral is locked in. When the surviving spouse eventually dies, the full value of the QTIP trust is pulled back into their taxable estate and taxed as if they had owned it outright.2Office of the Law Revision Counsel. 26 USC 2044 – Certain Property for Which Marital Deduction Was Previously Allowed The surviving spouse’s own exemption then absorbs the tax.
A bypass trust uses the deceased spouse’s exemption immediately. Assets up to the exemption amount are funded into the trust at the first death, consuming that exemption on the way in. Because the surviving spouse never owns the property, and their access to principal is limited to an ascertainable standard tied to health, education, support, or maintenance, the assets stay outside the surviving spouse’s taxable estate.3Office of the Law Revision Counsel. 26 U.S. Code 2041 – Powers of Appointment When the surviving spouse dies, whatever remains passes directly to the named beneficiaries with no additional estate tax. Those assets have effectively skipped both estates.
For 2026, each individual has a $15 million basic exclusion amount, indexed for inflation going forward, so a married couple can potentially shelter $30 million.4Office of the Law Revision Counsel. 26 U.S. Code 2010 – Unified Credit Against Estate Tax Consider a couple worth $20 million. If the first spouse leaves everything to the survivor through a QTIP or outright, the survivor’s estate is roughly $20 million. The $15 million exemption absorbs most of it, but $5 million faces the 40% estate tax. If instead the first spouse funds a bypass trust with $15 million, only $5 million remains in the survivor’s estate, comfortably under their own exemption. No federal estate tax at all.
The Cost Basis Trade-off Most People Miss
Estate tax dominates the conversation, but for many couples the income tax consequences matter more. Assets included in a decedent’s taxable estate generally receive a step-up in cost basis to fair market value at the date of death, wiping out built-in capital gains. QTIP trust assets get this step-up twice: once at the first spouse’s death, then again when the assets are pulled back into the surviving spouse’s estate under Section 2044.2Office of the Law Revision Counsel. 26 USC 2044 – Certain Property for Which Marital Deduction Was Previously Allowed Heirs who sell shortly after inheriting owe little or no capital gains tax.
Bypass trust assets do not get that second step-up. They are excluded from the surviving spouse’s estate on purpose, which is exactly why they escape estate tax, but the same exclusion locks in the cost basis from the first spouse’s death. If a bypass trust holds stock worth $500,000 when it was funded and $2 million decades later when the surviving spouse dies, beneficiaries inherit a $1.5 million built-in capital gain.
For estates comfortably under the combined exemption, this trade-off can turn a bypass trust into a net negative. You saved zero estate tax because there was none to pay, and you handed your heirs a capital gains bill that a QTIP structure would have avoided.
Control Over Who Ultimately Inherits
Both trusts let the first spouse lock in the final beneficiaries. The surviving spouse cannot redirect the assets in either structure. But QTIP trusts are practically built for blended families. A spouse with children from a prior relationship can provide the current spouse with lifetime income and still guarantee that the principal goes to those children. The remainder is fixed at the first death.
Bypass trusts also name remainder beneficiaries, but the trust can shrink during the surviving spouse’s lifetime because the trustee may distribute principal for health, education, support, or maintenance. That flexibility can create friction. Trustees are pulled between the surviving spouse’s needs and the remainder beneficiaries’ expectations, and disputes are not uncommon.
Creditor Protection
Bypass trusts are generally the stronger tool for shielding assets from creditors. The surviving spouse has no ownership and only a limited, standard-based right to principal, so creditors cannot reach the assets. A spendthrift clause adds further protection. Some states carve out exceptions for child support, alimony, and tax debts.
QTIP trusts are more exposed on this front. The surviving spouse has an absolute right to all income for life, and creditors in many jurisdictions can attach that income stream. The principal remains protected for the remainder beneficiaries, but the income is fair game.
Why Portability Shifted the Default
Before 2011, a bypass trust was essentially mandatory for any couple that wanted to use both spouses’ estate tax exemptions. Leaving everything outright to the survivor wasted the first spouse’s exemption. Portability changed that. The executor of the deceased spouse’s estate can now elect to transfer any unused exclusion to the surviving spouse, who then has their own exemption plus the deceased spousal unused exclusion (DSUE).4Office of the Law Revision Counsel. 26 U.S. Code 2010 – Unified Credit Against Estate Tax The election requires filing Form 706 within nine months of death, with a possible six-month extension, even when no tax is owed.
Portability made bypass trusts unnecessary for many couples whose only goal was preserving both exemptions. But portability has limits. The DSUE amount is not indexed for inflation once locked in, so it stays flat while the survivor’s own exemption grows. Portability does not apply to the generation-skipping transfer tax exemption, so families planning for grandchildren still need trust-based strategies. And portability does nothing for asset protection or controlling where property goes at the second death.
The trap here is assuming portability makes bypass trusts obsolete. For a couple with $10 million and aligned family goals, it often does. For a couple with $25 million, children from prior marriages, or concerns about the survivor’s future creditors, it does not.
When a QTIP Trust Is the Better Choice
A QTIP trust tends to win when the priority is controlling who inherits rather than minimizing estate tax. Blended families are the classic example. The current spouse gets lifetime income, the children from the prior marriage get certainty about the principal, and neither can be cut out.
QTIP trusts also win when the combined estate is likely to fall within the combined exemption. The double step-up in basis can save beneficiaries far more in capital gains tax than a bypass trust would save in estate tax, which in that scenario is zero anyway. A couple with $12 million in highly appreciated real estate or concentrated stock often comes out ahead with QTIP planning even though it does not “shelter” anything from estate tax.
The QTIP election also offers timing flexibility. Because the executor makes the election after death, the family can look at current tax law, asset values, and the survivor’s finances before deciding how much property to elect. Property not elected as QTIP does not qualify for the marital deduction and functions much like a bypass trust.1Office of the Law Revision Counsel. 26 U.S. Code 2056 – Bequests, etc., to Surviving Spouse This partial QTIP election gives the family a planning lever that a pure bypass plan lacks.
When a Bypass Trust Is the Better Choice
A bypass trust is the better tool when the combined estate is large enough that both exemptions need to work at the same time. A couple with $28 million relying on portability holds $28 million in the survivor’s estate against a single ported exemption. That works today, but if the estate grows or exemption law contracts, the margin disappears. Funding a bypass trust at the first death removes those assets from the tax system regardless of what happens later.
Bypass trusts also serve families using the generation-skipping transfer tax exemption, which is not portable. Allocating the deceased spouse’s GST exemption to a bypass trust can protect assets across multiple generations.
Creditor protection is the other strong case. If the surviving spouse works in a profession with litigation risk, faces potential future divorce, or has spending patterns that worry the first spouse, a bypass trust keeps assets out of reach in ways outright ownership and even a QTIP structure cannot.
Using Both Trusts Together
Many estate plans use both structures. A common split funds a bypass trust with an amount equal to the deceased spouse’s estate tax exemption and directs the remaining assets to a QTIP trust. The bypass side permanently shelters assets up to the exemption. The QTIP side defers tax on everything above that, uses the marital deduction, and preserves the second step-up in basis for those assets.
More flexible plans name a QTIP trust as the default and give the executor discretion to make a partial QTIP election based on the situation at the first death. The portion for which QTIP treatment is not elected effectively becomes a bypass trust, funded at whatever amount looks optimal after the fact rather than locked in years earlier when the estate plan was signed.