"Buy, borrow, die" is not a product, a loophole, or a single legal maneuver. It's a description of three ordinary, individually unremarkable choices, made in sequence, that together produce a specific tax outcome. And as of a law change less than two months before this page was last verified, one of the three steps just got permanently larger for a much wider set of estates than before.
The three steps
Buy appreciating assets, most commonly securities, and hold them.
Borrow against those assets when you need cash, rather than selling them. Securities-based lending (SBL), described in detail on this site's SBL guide, lets you access liquidity using the portfolio as collateral. Loan proceeds are not income under federal tax law. Selling the stock would realize a taxable capital gain; borrowing against it, without selling, does not.
Die holding the appreciated assets rather than the cash from selling them. Under IRC Section 1014, the cost basis of an inherited asset generally steps up to its fair market value on the date of death. If your heirs later sell at that stepped-up value, the capital gain that built up during your entire lifetime is largely erased for income tax purposes. The appreciation is never taxed as a capital gain to you or, on that portion, to them.
What actually happens to the loan
The loan does not vanish at death. It remains a liability of the estate and is typically settled from estate assets, often including some of the very securities that were pledged as collateral, before the remainder passes to heirs at their new, stepped-up basis. The strategy defers and, on the appreciation itself, effectively eliminates income tax exposure. It does not erase the debt, and settling that debt is a real, sometimes disruptive event for an estate to manage.
The limitation almost every popular summary skips: estate tax
Step-up in basis under IRC Section 1014 addresses capital gains tax. It has nothing to do with estate tax, a separate tax on the value of an estate above an exemption threshold. As of a 2025 law change, the One Big Beautiful Bill Act, signed July 4, 2025, the federal estate and gift tax exemption was permanently raised to $15 million per individual, $30 million for a married couple, effective January 1, 2026, with no scheduled sunset and inflation indexing beginning in 2027.
That is a large enough threshold that most households never approach it. But for an estate that exceeds it, the excess above $15 million (or $30 million joint) still owes estate tax, calculated independently of whatever basis adjustments happened on the underlying assets. A stepped-up basis that eliminates capital gains tax on $50 million of appreciation does nothing to shield an estate above the exemption from estate tax on that same value. These are two separate taxes, addressed by two separate mechanisms, and conflating them is the single most common error in casual explanations of this strategy.
Where it actually breaks
The strategy's central assumption, that you can keep borrowing against appreciating collateral indefinitely without ever needing to sell, depends entirely on the collateral actually holding its value, or at least not falling far enough to trigger a forced sale. This site's margin-call mechanics guide works through exactly how small a price decline can trigger a call relative to how large it feels like it should need to be. A joint FINRA/SEC investor alert specifically warns that many SBL loans are structured as demand loans, callable at the lender's discretion regardless of payment history. A borrower forced to sell pledged collateral to meet a call during a market downturn realizes the exact capital gain the entire strategy was designed to defer, at the single worst moment to realize it.
The strategy also assumes ongoing access to credit on reasonable terms. A lender that tightens advance rates, raises rates, or declines to renew a line at renewal time can force the same outcome without a market downturn at all.
Who this actually applies to
The core mechanism, borrow instead of sell, scales down well below the level where anyone would call it a billionaire's strategy. A retail investor with a modest margin loan against a brokerage account is doing a smaller-scale version of the same thing. What changes at higher wealth levels is the sophistication of the lending relationship (Lombard lines, custom credit, multi-lender facilities) and, materially since 2026, whether the estate-tax exemption threshold is even a live consideration at all for that household.
What to run before relying on this
Run the actual numbers, not a rule of thumb, through the Borrow vs Sell calculator: enter your own cash need, portfolio value, and loan terms to see whether borrowing or selling actually leaves you wealthier over your real time horizon.
- Model what happens to your specific loan, and your ability to service or roll it, under a 30% and a 50% decline in your pledged collateral, not just the current market environment.
- Confirm with your own advisor whether your estate is realistically likely to approach the $15 million (or $30 million joint) 2026 federal exemption threshold, since that determines whether the estate-tax half of this strategy is even relevant to you.
- Ask what specifically happens to any outstanding loan balance at your death under your current estate plan, and whether your heirs would need to sell pledged assets to settle it.
- Review, separately, whether interest on your specific borrowing is likely to be deductible at all, covered on this site's interest-deductibility tracing guide, since that is a distinct question this page does not resolve.