# Portability of estate tax exemption after sunset

This is a question about the federal estate tax in the United States.

Suppose a married man died in (let's say) 2021, when the estate tax exemption was \$11.7 million. He leaves his entire estate to his wife taxfree. She dies in 2023, when the exemption is (say for simplicity) still \$11.7 million. When the wife dies, she is entitled to both his and her exemptions, for a total of \$23.4 million.

Now suppose instead that the man dies in 2021, leaving everything to his wife taxfree, and that she dies in 2026, after the exemption reverts to \$5 million.

Once again, she is entitled to both exemptions. Does her total exemption amount to \$11.7 million plus \$5 million, or does it amount to \$5 million plus \$5 million? In other words, is the value of the ported exemption equal to the value of an exemption at the time of the first spouse's death or at the time of the second spouse's death?

• I believe she would have to file for/claim his remaining exemption when he dies, not later when she dies. Or at least when filing their tax return the year he died. If she waits until she dies before claiming it, she will only get her own exemption. But I don't have the sources on-hand to back this up (will convert to answer if I find them, or delete if I am spreading misinformation) Commented Jun 24, 2022 at 20:41
• @yoozer8: But this doesn't really answer my question. Suppose she claims the exemption when her husband dies. At that time the exemption is 11.7 million. She dies in 2026, when the exemption is 5 million. At that point, is the exemption she claimed from her husband worth 11.7 million or 5 million? Commented Jun 24, 2022 at 20:42
• It's currently \$10m plus inflation from 2010 = \$11.7m for 2021, and if current law is unchanged will revert in 2026 to \$5m plus inflation from 2010 which is not yet known but I have seen estimates of \$6.2m. See 26USC2010(c)(3). Commented Jun 26, 2022 at 2:31