Step-Up in Basis: How Inherited Assets Reset Their Cost Basis

An inherited asset generally gets a new cost basis equal to its fair market value on the date of death — erasing whatever capital gain built up while the person who died owned it. This single rule, tucked into IRC §1014, is one of the most valuable and least understood provisions in the entire tax code, and it produces a genuinely different outcome depending on whether an appreciated asset is given during life or left at death.

The Basic Mechanic

Cost basis is the number used to calculate capital gain or loss when an asset is eventually sold — generally what was originally paid for it, adjusted over time. When someone dies owning an appreciated asset — stock, a home, a stake in a private company — the person who inherits it does not inherit the original, low basis. They receive a new basis equal to the asset's fair market value on the date of death (or, if the executor elects it, an alternate valuation date six months later). Whatever gain accrued during the decedent's lifetime simply disappears for tax purposes — it is never taxed to anyone.

A worked example: a parent bought stock decades ago for $50,000; at death it's worth $2,000,000. If the parent had sold it the day before dying, the $1,950,000 gain would have been fully taxable. Instead, the heir inherits it with a basis of $2,000,000 — the parent's original $1,950,000 gain is permanently erased. If the heir sells immediately at $2,000,000, there is no taxable gain at all. This example is illustrative only and does not reflect any specific estate.

Gift vs. Inheritance: A Fundamentally Different Result

This is the comparison most people miss when deciding whether to give an appreciated asset during life or leave it at death. A lifetime gift does not get a step-up — the recipient takes the donor's original, carryover basis. Using the same example: if the parent gifts the stock during life instead of leaving it at death, the recipient's basis remains $50,000, not $2,000,000. If the recipient later sells at $2,000,000, they owe capital gains tax on the full $1,950,000 of built-in gain that a step-up would have erased entirely. All else equal, holding a highly appreciated asset until death is far more tax-efficient for the recipient than gifting it during life — though other factors (need for current income, estate size relative to the exemption, control considerations) can outweigh this basis difference in a specific situation.

The "Step-Down" Risk

Basis resets in both directions. An asset that has declined in value gets a lower basis at death, not the original higher one — permanently erasing any built-in loss along with any built-in gain. This is a reason some estate planners recommend selling a loss position before death (to use the loss on the decedent's own final return) rather than holding it and letting the basis step down to a lower value that eliminates the loss for everyone.

California's Community Property Advantage: A Full Step-Up on Both Halves

For married couples in a community property state — California among them — the step-up rule produces a materially better result than in a common-law state. Community property receives a full step-up in basis on both halves of the property when either spouse dies, not just the deceased spouse's half. In a common-law state, only the decedent's half of jointly-held property typically receives a step-up; the surviving spouse's half retains its original basis.

Applied to the earlier example: a California couple holding $2,000,000 of community-property stock with a $50,000 combined basis receives a full $2,000,000 basis on the entire position when the first spouse dies — even though the surviving spouse continues to own their half. In a common-law state, only the deceased spouse's half (economically, roughly $1,000,000 of value) would step up, while the surviving spouse's half retains its original, low basis until the second death. For a tech-worker couple holding a large, long-appreciated position — often concentrated employer stock — this is a significant, easy-to-overlook advantage of California's community property system, and a reason properly titling assets as community property (rather than as separate or joint tenancy property) matters.

Portability and Step-Up Are Separate Concepts

It's worth being explicit that step-up in basis and the federal estate tax exemption's portability feature are two different mechanisms addressing two different taxes. Step-up affects income tax basis (what's owed if the asset is later sold); the estate tax exemption and its portability affect estate tax (what's owed on the estate itself at death). An estate well below the federal exemption still receives a full step-up in basis — the two provisions operate independently.

What This Page Does Not Cover

This page covers the step-up mechanic itself. For how this interacts with a jointly-held revocable trust and California's community property funding requirements in more detail, see Trusts for Tech Workers. For the separate question of how much an estate can pass free of federal estate tax, see Estate Tax Exemption. For general capital gains mechanics once an asset is eventually sold, see Capital Gains Taxes and Cost Basis.

California Note

California conforms to the federal step-up rule and adds its own significant benefit through community property treatment, as described above. California has no separate state estate tax, so the step-up in basis is the primary tax benefit California residents receive at death on appreciated assets — there is no offsetting state-level estate tax to weigh against it, unlike states such as Oregon or Massachusetts that impose their own estate tax at much lower thresholds than the federal exemption.

This article is for educational purposes only and does not constitute legal, tax, or financial advice. Basis step-up rules depend on how an asset is titled, the applicable state's marital property law, and the specific facts of an estate. Always consult a qualified estate planning attorney or tax advisor, particularly when deciding whether to gift an appreciated asset during life or retain it for a step-up at death.