The step-up in basis: the tax break for dying with appreciated assets

Here is one of the strangest, most valuable rules in the tax code: when you die, most of your assets get their cost basis reset to the market value on your date of death. The unrealized gain that built up during your life — sometimes decades of it — simply vanishes for tax purposes. Your heirs can sell the next day and owe capital gains tax on essentially nothing. It is called the step-up in basis, and understanding it changes how you should think about gifting, selling, and which assets to spend first.

How it works, in one example

Say your mother bought a stock for $20,000 in 1990. By the time she dies it is worth $200,000. If she had sold it while alive, she would owe capital gains tax on the $180,000 gain. Instead she leaves it to you. Your basis 'steps up' to $200,000. You sell it the next week for $201,000 and owe tax only on the $1,000 of growth since her death. The other $180,000 of gain is never taxed by anyone. That is the step-up.

What gets a step-up — and what does not

The double step-up for married couples

In the nine community property states, when one spouse dies the ENTIRE community-property asset can step up — not just the deceased spouse's half. In common-law (separate property) states, only the deceased spouse's half steps up, though titling assets as joint tenants or using certain trusts affects the outcome. This is a genuine, if unglamorous, reason couples in community property states sometimes hold appreciated assets jointly rather than separately.

How this should shape real decisions

1. Spend-down order in retirement: often it makes sense to spend cash and tax-deferred accounts while letting highly appreciated taxable assets ride to death for the step-up — balanced against required minimum distributions and bracket management.
2. Gifting to heirs: gift cash or high-basis assets during life; save low-basis, highly appreciated assets to pass at death.
3. Elderly relatives holding old positions: encourage them NOT to sell a lifetime of appreciation just to 'simplify' if death may make that gain disappear — the tax cost of selling can be enormous and avoidable.
4. Charitable giving reverses the logic: appreciated assets are the BEST thing to donate (the charity pays no tax and you skip the gain), so donate the low-basis holdings and keep the high-basis ones.

The bottom line

The step-up in basis rewards patience with appreciated assets: for most families under the estate-tax exemption, holding a low-basis stock, fund, or property until death erases the built-up gain entirely. It reshapes gifting strategy (give high-basis, bequeath low-basis), retirement spend-down order, and charitable choices. Retirement accounts are the big exception — no step-up, ordinary income to heirs. Map your assets by basis before making big sell-or-gift decisions, and loop in a CPA where the numbers are large.