When someone inherits a house or a brokerage account, the tax code performs a quiet erasure. The asset’s cost basis — the figure used to calculate taxable gain — is reset to its fair market value on the day the previous owner died, so decades of appreciation that would have been taxable if the original owner had sold simply disappear from the ledger. An heir who sells soon afterward owes capital-gains tax only on any increase since that date, which is often little or nothing. This adjustment, known as a step-up in basis, is one of the most consequential and least understood mechanics in inheritance.
How basis is reset at death
Basis is normally what an owner paid for an asset, and gain is the difference between that cost and the sale price. The IRS explains in Topic 703 that assets acquired other than by purchase — including inheritances — follow a different rule: the basis of stocks, bonds or property received without buying them is generally determined by their fair market value on the date of transfer. For inherited property that transfer date is the decedent’s death, and the IRS guidance on gifts and inheritances confirms the basis is the fair market value of the property on the date the owner died.
A worked example shows the size of the effect. Suppose a couple bought a home decades ago for $60,000 and it is worth $400,000 when one of them dies. Had the owner sold during life, the gain subject to tax would have been measured from the $60,000 cost. An heir who inherits it instead takes a basis of $400,000, so selling near that price produces almost no taxable gain — the roughly $340,000 of lifetime appreciation is never taxed as capital gain. The same reset applies to inherited stocks and mutual-fund shares valued at their date-of-death price.
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The alternate valuation date and its condition
The date of death is the default, but it is not the only option. The IRS allows an estate to use an alternate valuation date instead — a value measured months after death rather than on the day itself — which can matter when markets or property values shift during the settling of an estate. That election is not automatic and not available to an heir acting alone: it applies only if the executor of the estate files a federal estate tax return, Form 706, and specifically elects the alternate valuation on that return. Absent that filing and election, the basis stays fixed at the fair market value on the date of death.
Because the exact figure drives the eventual tax bill, the IRS points heirs to the executor for the fair market value of inherited property as of the death date, and to Publication 551, Basis of Assets for the detailed rules. Establishing that value carefully — through an appraisal for real estate or documented closing prices for securities — is what lets an heir later prove the stepped-up basis to the IRS and claim the erased gain rather than guessing and overpaying.
Which assets miss the reset
The step-up is powerful but selective, and assuming it covers everything is a costly error. Tax-deferred retirement accounts do not receive it: money in a traditional IRA or 401(k) was never taxed on the way in, so heirs generally owe ordinary income tax on withdrawals, with no basis reset to shield the growth. Assets given away during the owner’s lifetime also miss out — a gift carries the giver’s original basis to the recipient, which is why transferring a house to children before death can produce a far larger tax bill than letting them inherit it. The reset is a benefit of inheriting, not of receiving.
There is also a guardrail against inflating the number. A 2015 law requires, in certain cases, that an heir’s basis be consistent with the value finally determined for federal estate tax purposes, and an executor may send a Schedule A to Form 8971 reporting that value. Claiming a basis higher than the estate’s established figure can trigger an accuracy-related penalty, so the stepped-up value has to match what the estate reported rather than being set to whatever minimizes the heir’s gain.
When the sale is reported
The reset does not remove the paperwork. When an heir sells inherited property, the proceeds are generally reported, and any gain above the stepped-up basis is figured on Schedule D and Form 8949. If the sale price sits at or below the date-of-death value, the calculation frequently shows little or no taxable gain — and inherited property that has been held is generally treated as long-term, taxed at the lower long-term capital-gains rates rather than as ordinary income.
The upshot is a rule that quietly rewards inheriting an appreciated asset over receiving it as a gift, and rewards knowing its date-of-death value over losing track of it. The gain that vanishes is real money that would otherwise be taxed, but capturing it depends on two unglamorous steps: confirming the asset qualifies for the step-up, and pinning down the fair market value on the date of death before that figure becomes impossible to reconstruct.
This article was researched and drafted with the assistance of artificial intelligence.
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