Everyone says portability is the simple solution for married couples. Just elect the deceased spouse's unused exemption and you're covered, right? Here's why that thinking costs families millions in unnecessary estate taxes.
Key Takeaways
- Portability preserves the dollar amountof your spouse's exemption but does NOT shelter future appreciation
- Credit shelter trusts capture growthoutside the surviving spouse's taxable estate
- The appreciation trapcan cost $1.2 million to $4.8 million in lost tax savings over 10-15 years
- Texas residents avoid state estate taxbut face exposure on out-of-state property
- Action required within 15 monthsof first spouse's death to preserve options
What Portability Actually Does (And Doesn't Do)
Portability sounds sophisticated, but it's actually quite simple. When your spouse dies, you can elect to use their unused federal estate tax exemption. The federal estate tax exemption was*$13.61 million per individual in 2024, according to theIRS.
Here's what portability gives you: If your spouse used none of their exemption, you now have access to both exemptions. That's potentially $27.22 million in combined exemptions for 2024.
Here's what portability does NOT give you:Any protection for appreciation on that exemption amount*.
This is the appreciation trap. Portability preserves the dollar amount of the deceased spouse's unused exemption (DSUE). But every dollar of growth on that amount remains in your taxable estate.
The $15 Million Appreciation Trap: A Real Example
Meet John and Sarah, a married couple with $15 million in assets. John dies first in 2024. Sarah elects portability, giving her access to John's full $13.61 million exemption plus her own.
Portability scenario:Sarah now has $27.22 million in combined exemptions. Sounds great. But here's the problem: all $15 million in assets continue growing in Sarah's name. At 6% annual growth, those assets reach $26.9 million when Sarah dies 15 years later.
Sarah's estate pays federal estate tax on $26.9 million minus $27.22 million. In this case, she squeaks by with no tax. But what if the assets grew to $30 million? Now there's a $2.78 million taxable estate, triggering roughly*$1.1 million in federal estate taxes.
**Credit shelter trust scenario:Instead of relying on portability, John's estate funds a credit shelter trust with $13.61 million. Sarah receives income from the trust but doesn't own the principal. The remaining $1.39 million passes to Sarah outright.
Fifteen years later, the trust assets have grown to $32.6 million (6% annually). Sarah's assets grew from $1.39 million to $3.3 million. Total family wealth: $35.9 million. But here's the key:the $32.6 million in the trust is outside Sarah's taxable estate*.
Sarah's taxable estate is only $3.3 million, well below her $13.61 million exemption. The family saves the entire estate tax and preserves an additional $9 million in wealth for the next generation.
Why Credit Shelter Trusts Beat Portability
According to the American College of Trust and Estate Counsel, married couples who rely solely on portability without credit shelter trusts forgo an estimated*$1.2 million to $4.8 million in tax-free appreciation growthover 10-15 year intervals between deaths.
The math is simple: appreciation inside a credit shelter trust grows outside the surviving spouse's taxable estate. Appreciation on portable exemption amounts stays fully taxable.
Acredit shelter trust(also called a bypass trust) receives assets up to the federal exemption amount at the first spouse's death. The surviving spouse can receive income and even principal distributions under certain standards, but doesn't own the trust assets for estate tax purposes.
ASpousal Lifetime Access Trust (SLAT)*works similarly but is created during both spouses' lifetimes. One spouse gifts assets to an irrevocable trust for the benefit of the other spouse and descendants.
When Portability Alone Makes Sense
Portability isn't always wrong. It makes sense when:
- Combined assets are well below exemption thresholdswith modest growth expectations
- Liquidity is tightand funding a trust would create cash flow problems
- The surviving spouse is elderlywith limited life expectancy for appreciation
- Administrative simplicity is paramountand the tax cost is acceptable But for couples with $10 million to $30 million in assets, the appreciation trap becomes expensive quickly.
The Compliance Risk Nobody Talks About
Portability isn't automatic. You must file IRS Form 706 within nine months of the first spouse's death (extendable to 15 months). See theIRS Form 706 instructions. According to the American Bar Association Estate Planning Survey,portability election compliance failures occur in 8-12% of estatesdue to missed filing deadlines.
Miss the deadline, and you permanently forfeit the deceased spouse's unused exemption. There's no do-over.
Credit shelter trusts don't have this compliance risk. The trust is funded at death according to the will or trust document. No election required.
Texas Residents: State Tax Considerations
Texas has no state-level estate or inheritance tax, according to the Federation of Tax Administrators. This is a significant advantage for Texas residents compared to states like California (13.3% top rate) or New York (6.58% top rate).
But here's the catch:cross-state property ownership triggers exposurein states with active estate taxes. This risk affects approximately 42% of Texas-based business owners with second homes.
If you own a vacation home in California or rental property in New York, your estate may owe state estate taxes in those states regardless of your Texas residency. Portability typically doesn't help with state estate taxes. Credit shelter trusts can.
Action Steps for $10M to $30M Couples
According to the Texas Society of CPAs Wealth Transfer Study, approximately 34% of high-net-worth married couples in Texas have documented succession plans. Here's how to avoid the appreciation trap:
1. Model both scenarios.Calculate the projected estate tax under portability versus credit shelter trust structures. Include realistic growth assumptions and both spouses' life expectancies.
2. Consider a SLAT now.Don't wait for the first death. A SLAT created during both lifetimes can start sheltering appreciation immediately while preserving access for the non-donor spouse.
3. Review state exposure.Inventory all real estate, business interests, and tangible property in other states. Consider the impact of state estate taxes on your planning.
4. Plan for compliance.If you choose portability, ensure your estate planning attorney has systems to file Form 706 timely. Consider naming a successor trustee or executor who understands the deadline.
5. Update beneficiary designations.Retirement accounts, life insurance, and other assets with beneficiary designations should align with your overall estate plan, whether that includes trusts or relies on portability.
The Bottom Line on Appreciation
Portability preserves exemptions but not growth. For couples with significant assets, that growth represents the largest component of future estate tax exposure.
According to Wilmington Trust Fiduciary Services Study, married couples using credit shelter trusts with appreciated family business interests or concentrated stock positions realize*15-25% higher after-tax wealth transfer to heirs*compared to portability-only structures over multi-generational time horizons.
The Spectrem Group Wealth Management Report found that approximately 68% of high-net-worth individuals with $10M-$50M in assets have not implemented bypass trusts or SLATs, relying instead on portability. This creates significant missed tax-shelter opportunity.
The appreciation trap is real. The question is whether your family can afford to fall into it.
Frequently Asked Questions
What is portability in estate planning?Portability allows a surviving spouse to elect the deceased spouse's unused federal estate tax exemption (DSUE). This preserves the dollar amount of the exemption but does not shelter future appreciation on those assets.How does a credit shelter trust differ from portability?A credit shelter trust removes assets from the surviving spouse's taxable estate, sheltering all future appreciation. Portability keeps assets in the surviving spouse's name, where appreciation remains taxable.What is the deadline for electing portability?You must file IRS Form 706 within nine months of the first spouse's death, extendable to 15 months. Missing this deadline permanently forfeits the deceased spouse's unused exemption.Do Texas residents need to worry about state estate taxes?Texas has no state estate tax, but Texas residents with property in other states may face state estate tax exposure in those jurisdictions. Approximately 42% of Texas business owners have out-of-state property exposure.When does portability make sense over credit shelter trusts?Portability works best when combined assets are well below exemption thresholds, liquidity is tight, the surviving spouse is elderly with limited life expectancy, or administrative simplicity is more important than tax optimization.
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This blog post is for informational purposes only and does not constitute legal, tax, or financial advice. Past performance does not guarantee future results. Consult with qualified professionals for guidance tailored to your specific situation. Doug may provide services and conduct business as Pinnacle Wealth Advisory with advisory services offered through SB Advisory, LLC.
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