Portability Doesn’t Happen Automatically
Portability allows a surviving spouse to use any “leftover” estate tax exclusion from the first spouse to die. It’s a powerful estate planning technique, according to a recent article in Think Advisor, “This Estate Tax Filing Mistake Can Cost Clients Millions.” However, portability doesn’t happen automatically.
To secure portability, the executor of the first deceased spouse’s estate must file a Form 706—known as an estate tax return—to elect portability, and it must be filed in a timely manner and be properly prepared.
This is necessary even if no estate tax is otherwise due from the deceased spouse’s estate. Given the high federal estate tax exemption, most affluent couples nearing the threshold don’t need to file the form. However, it’s still worth filling it out. Here’s why.
A husband who dies with $5 million in assets passes that along to his wife, who may have $10 million of her own. If she lives another 20 years and is invested in markets, her wealth upon her death could be very close to or over the maximum estate tax exemption for a single person. If she secures portability at the time of her husband’s death, she can use his remaining estate tax exemption amount and avoid significant estate tax when passing wealth onto her heirs.
Even if the first spouse to pass doesn’t come close to the federal estate tax threshold, it still makes sense to take the right steps to secure portability. A recent Tax Court case illustrates how this can go wrong if not done correctly. A successful midwestern business owner died, and the form wasn’t filled out correctly. The filing mistake cost heirs an additional $1.5 million in estate taxes from the surviving spouse’s estate.
The deadline to elect portability of a deceased spouse’s unused federal estate tax exemption is nine months after the date of death. While your estate planning attorney can request a six-month extension, it’s best to do this in a timely manner. If the estate isn’t otherwise required to file an estate tax return, you can use the Revenue Procedure 2022-32. This was added after many estates failed to file for portability because they didn’t realize it was needed until after the federal estate tax return was due.
This process is not easy and involves several important steps, especially if any of the first-to-die spouse’s assets flow to anyone other than the surviving spouse or a charity. In these situations, assets flowing out of the first estate must be assigned a fair market value using a valuation professional.
The IRS provides a valuation method for estates filing solely to capture portability. An executor may use a good-faith estimate of the value. However, securing a professional valuation may be recommended by your estate planning attorney.
The Tax Court case referred to above illustrates how this process can go wrong. The assets passed down by the first spouse to die went to other family members, not her spouse or a charity. A proper valuation was not done. The executor also applied for an automatic extension to file Form 706 but failed to mail the return until five months after the extended deadline. There are some instances when the IRS provides a “safe harbor” for late filing. However, this only applies when the value of the first deceased spouse’s estate is less than the applicable exclusion amount. The return was not complete, nor was it properly prepared.
Portability is a beneficial option and shouldn’t be missed, even when it seems unlikely to be needed. Just remember – portability doesn’t happen automatically. An experienced estate planning attorney should be consulted to protect the estate upon the death of the first spouse to secure portability. If you would like to learn more about portability and estate planning, please visit our previous posts.
Reference: Think Advisor (October 15, 2025) “This Estate Tax Filing Mistake Can Cost Clients Millions”
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