What Is a Step-Up in Basis?
Inheriting stock or a house comes with a tax detail that surprises a lot of people, and usually in a good way: the tax history of the asset often gets reset the moment it changes hands.
The short answer
A step-up in basis adjusts the “cost basis” of an inherited asset to its value at the time of the original owner’s death, rather than what that person originally paid for it. This matters because cost basis is what’s used to calculate gain or loss when the asset is eventually sold — a higher basis generally means a smaller taxable gain if the heir sells.
Why cost basis matters in the first place
Whenever an asset like stock, a house, or other property is sold, the taxable gain is generally the difference between the sale price and the cost basis — usually what was originally paid, plus certain adjustments over time. If someone bought stock decades ago at a low price and it grew substantially, selling it while still alive would mean paying tax on that entire increase, similar to how capital gains taxes work on any investment sale.
How the step-up changes the picture
When that same stock is inherited instead of sold by the original owner, its basis is typically adjusted upward to reflect its value on the date of death — not the original purchase price. If the heir then sells the asset soon after inheriting it, there may be little or no taxable gain at all, because most of the appreciation that happened during the original owner’s lifetime is effectively wiped from the calculation for tax purposes.
An illustrative example
Say someone bought shares years ago for a low price and held them until they had grown substantially in value by the time they passed away. Without a step-up, an heir who later sold those shares would owe tax on the full increase since the original purchase. With the step-up, the basis resets to the value at the date of death, so the heir would typically only owe tax on any further growth that happens after they inherit it, not the growth that occurred before.
How it connects to estate tax and inheritance
The step-up in basis is a separate mechanism from estate tax, though both come into play around the same event. An estate might owe no estate tax at all — since most estates fall under the applicable threshold — while the assets passed to heirs still receive the basis adjustment. This is one reason the difference between inheritance tax and estate tax is worth understanding separately from how basis adjustments work, since they’re governed by different rules entirely.
What to weigh
The step-up in basis is one of the more consequential rules in estate planning, particularly for families holding long-held appreciated assets like real estate or stock. Whether and how it applies can depend on the type of asset, how it’s titled, and current tax law, all of which are worth confirming with up-to-date guidance rather than assuming a past understanding still holds.