Idaho does not have an estate tax. The state also does not collect an inheritance tax, so nothing is owed to Boise when someone dies, regardless of the size of the estate or who inherits. The only death tax that can reach an Idaho estate is the federal estate tax, and it applies only to estates worth more than $15 million in 2026.
No Inheritance Tax Either
The two taxes often get confused, and the distinction matters when you’re trying to figure out what you might owe. An estate tax is calculated on the total value of a deceased person’s assets before anything is distributed. An inheritance tax is paid by each heir individually, based on what that person receives, and the rate sometimes depends on how closely the heir was related to the deceased. Six states still charge inheritance tax. Idaho is not one of them.1Idaho State Tax Commission. Estates and Taxes
Whether you inherit from a parent, a sibling, a spouse, or a friend, the state of Idaho charges nothing on the transfer. The value of the house, the retirement account, the farmland, or the cash is yours to receive without a state-level cut.
The Federal Estate Tax Threshold
Federal estate tax rules apply to Idaho residents the same way they apply to everyone else in the country. The threshold is the basic exclusion amount, and only the portion of an estate that exceeds it gets taxed.
For deaths occurring in 2026, the basic exclusion is $15 million per individual.2Internal Revenue Service. What’s New – Estate and Gift Tax That figure jumped after the One, Big, Beautiful Bill was signed into law on July 4, 2025. The legislation set the exclusion at $15 million and indexed it to inflation, so the threshold will rise automatically in future years.3Office of the Law Revision Counsel. 26 USC 2010 – Unified Credit Against Estate Tax The top federal rate on anything above the exclusion is 40 percent. For the overwhelming majority of Idaho families, the federal estate tax never comes into play.
Portability Doubles the Exemption for Married Couples
Married couples can effectively double the exclusion through a provision called portability. When the first spouse dies, any portion of their $15 million exclusion they didn’t use can transfer to the surviving spouse. If the first spouse’s estate was worth $5 million, the remaining $10 million of unused exclusion is added to the survivor’s own $15 million, giving them up to $25 million in total exemption. At the maximum, a married couple can shield $30 million from federal estate tax.4Internal Revenue Service. Frequently Asked Questions on Estate Taxes
Portability does not happen automatically. The executor of the first spouse’s estate must file IRS Form 706 to elect it, even when the estate is far too small to owe any tax. The standard deadline is nine months after the date of death, with a six-month extension available.5Internal Revenue Service. Instructions for Form 706 Executors who miss that window may still qualify for a late portability election filed within five years of the death under IRS Revenue Procedure 2022-32. If no one ever files, the surviving spouse permanently loses the deceased spouse’s unused exclusion. That lost paperwork is one of the more expensive oversights in estate planning.
Idaho’s Community Property Step-Up in Basis
The most valuable tax rule for Idaho heirs has nothing to do with estate tax. Under federal law, the cost basis of inherited assets resets to fair market value at the date of death.6Office of the Law Revision Counsel. 26 USC 1014 – Basis of Property Acquired From a Decedent If a parent bought stock for $20,000 thirty years ago and it was worth $200,000 the day they died, the heir’s basis is $200,000. Sell the stock the next day at that price and no capital gains tax is owed. The $180,000 of appreciation is wiped clean.
Idaho residents get a bigger version of this benefit because Idaho is a community property state. In common-law states, when one spouse dies, only the deceased spouse’s half of jointly owned assets receives the step-up. The surviving spouse’s half keeps its original basis. In Idaho, both halves of community property receive a stepped-up basis when either spouse dies. A surviving spouse can sell an appreciated house or a long-held brokerage account soon after the death and owe little or nothing in capital gains tax. The double step-up applies automatically to community property with no special election required.
Idaho Income Tax on Estate Earnings
Receiving an inheritance in Idaho triggers no state income tax on the inheritance itself. Once the deceased person’s assets start earning income after the date of death, though, that income is taxable. Interest from bank accounts, dividends from investments, and rent from property all count. The estate itself becomes a separate taxpayer for those purposes.
A personal representative must file Idaho Form 66, the Fiduciary Income Tax Return, if a resident estate earns $600 or more in gross income during the tax year.7Idaho State Tax Commission. Income Tax for Fiduciaries The form reports income earned by the estate, not the value of the estate. Idaho taxes that income at a flat rate of 5.3 percent on amounts above $4,811.8Idaho State Tax Commission. Form 66 Fiduciary Income Tax Return Late filing draws a 5 percent monthly penalty up to a 25 percent cap, with interest at 6 percent for 2026.
Inherited retirement accounts are the common surprise. Receiving a house or a taxable brokerage account generally creates no income tax event. Distributions from a traditional IRA or 401(k), on the other hand, count as ordinary income to whoever receives them because the contributions were never taxed on the way in. Idaho taxes those distributions at the same 5.3 percent rate that applies to other income.9Idaho State Tax Commission. Individual Income Tax Rate Schedule That is income tax, not estate tax, but it is the tax bill most Idaho heirs will actually see.