The generation-skipping transfer (GST) tax exemption ($15 million per person in 2026) can shelter trust assets from GST tax across multiple generations. The choice of funding formula clause directly affects how the GST exemption can be allocated, which trusts can be made fully GST-exempt, and whether the personal representative has the flexibility to optimize the allocation after death.
Poor coordination between the funding formula and the GST exemption strategy can waste exemption, create partially exempt trusts (which complicate administration for decades), or foreclose allocation options that the family needs. Drafting the formula with GST considerations in mind is essential for families with multi-generational planning objectives.
How GST Exemption Allocation Works
The personal representative allocates the decedent’s GST exemption to specific trusts or transfers on the estate tax return (Form 706). Each trust receives an “inclusion ratio” based on the exemption allocated relative to the trust’s value. A trust with an inclusion ratio of zero is fully GST-exempt; distributions to grandchildren and more remote descendants incur no GST tax. A trust with an inclusion ratio of one is fully subject to GST tax. A trust with an inclusion ratio between zero and one is partially exempt, requiring complex accounting for every future distribution.
The goal is to produce trusts with an inclusion ratio of either zero or one. Partially exempt trusts should be avoided because they impose administrative burden for the life of the trust.
The Credit Shelter Trust as GST-Exempt Vehicle
In the standard two-trust estate plan, the credit shelter trust is the natural home for the GST exemption. Under current law (2026), the applicable exclusion and the GST exemption are both $15 million, so the credit shelter trust (funded with up to $15 million) can be fully sheltered by both the unified credit (from estate tax) and the GST exemption (from GST tax).
When the credit shelter trust is fully funded and the GST exemption is fully allocated to it, the trust becomes a multi-generational wealth transfer vehicle. Assets pass to children, grandchildren, and more remote descendants without estate tax or GST tax at any level. This is one of the most powerful benefits of the credit shelter trust.
To understand how this trust preserves the estate tax exemption across generations, explore the credit shelter trust.
The Reverse QTIP Election for Excess Exemption
When the decedent’s GST exemption exceeds the amount in the credit shelter trust (possible if the estate is not large enough to fully fund the credit shelter trust, or if future legislation decouples the exemption amounts), the excess exemption can be allocated to a QTIP trust through the IRC § 2652(a)(3) reverse QTIP election.
The reverse QTIP election treats the decedent (rather than the surviving spouse) as the transferor of the QTIP trust for GST purposes. This allows the decedent’s GST exemption to be allocated to the trust. Without the reverse QTIP election, the surviving spouse is treated as the transferor (because QTIP property is included in the surviving spouse’s estate under IRC § 2044), and only the surviving spouse’s GST exemption can be allocated.
The reverse QTIP election requires a separate QTIP trust. It cannot apply to a portion of a single trust. This means the estate plan must create at least two marital trusts to use the reverse QTIP election: one for the reverse QTIP election and one for the remaining marital share.
To understand how QTIP elections enable GST planning, explore QTIP trusts and the reverse QTIP election for GST planning.
How the Funding Formula Affects GST Allocation
The funding formula influences GST exemption allocation in three ways:
- Separate vs. undivided trusts. The GST exemption is most effectively allocated to a separate, identifiable trust. Funding formulas that create distinct trusts (all pecuniary and fractional mechanisms except the single fund) provide clean allocation targets. The single fund marital, where both shares exist as accounting fractions within one trust, complicates the allocation because the exempt and non-exempt portions are not held in separate trusts. The personal representative may need to sever the trust before allocating the exemption, adding complexity.
- Timing of the funding. The GST exemption is allocated on the estate tax return, which is due nine months after death (with extensions). If the funding formula uses date-of-distribution values (true worth), the trust values at the time of allocation may differ from the values when exemption is allocated, potentially creating partially exempt trusts if the allocation does not match the trust’s current value. Fairly representative and fractional approaches, which use date-of-death values, align more naturally with the exemption allocation timing.
- The “marital share frozen” problem. In a traditional pecuniary marital approach, the marital trust’s value is fixed at the date-of-death formula amount. Post-death appreciation accrues to the credit shelter (residuary) trust. If the credit shelter trust grows beyond the GST exemption before the return is filed, the personal representative cannot allocate enough exemption to make the trust fully exempt. The reverse pecuniary avoids this problem because the credit shelter trust’s value is the fixed pecuniary amount (equal to the exclusion, which equals the GST exemption under current law).
These interactions make the funding formula choice inseparable from the GST allocation strategy. The formula should be drafted with full awareness of how the exemption will be deployed.
Drafting Recommendations
For families with multi-generational planning objectives, the funding formula should be drafted with the following GST considerations:
- Avoid the single fund marital. If clean GST-exempt trusts are important, the undivided fraction creates allocation and administration complications.
- Consider the reverse pecuniary direction. Mechanisms 4 or 5 fix the credit shelter trust at the applicable exclusion amount. Under current law, where the exclusion equals the GST exemption, this produces a credit shelter trust perfectly sized for full GST exemption allocation.
- Create a separate reverse QTIP trust. If the plan includes a reverse QTIP election, create a separate QTIP trust for the reverse QTIP (distinct from any other marital trust). The funding formula should address how assets are divided among the multiple trusts.
- Authorize trust severance. Include language in the trust document authorizing the personal representative to sever trusts for GST allocation purposes if needed. IRC § 2642(a)(3) and the regulations permit severance of a single trust into separate trusts with different inclusion ratios.
Addressing these considerations during drafting prevents the personal representative from facing allocation constraints that could have been avoided with better document design.
To compare how all eight funding mechanisms affect flexibility, gain recognition, and administration, explore the side-by-side funding formula comparison.