The BOXX ETF tax treatment is built around deferral: the fund pays no distributions, so no tax is owed until you sell your shares, and the gain you eventually realize is treated as a capital gain rather than as ordinary interest income. Since its December 2022 launch, the Alpha Architect 1-3 Month Box ETF has not paid a single taxable distribution. For a taxable account, that turns a cash-like holding into something closer to a growth position for tax purposes. The advantages are real, but they depend on how long you hold, where you live, and on an unresolved question about how the IRS views the underlying strategy.
Why BOXX Doesn’t Generate a Yearly Tax Bill
A Treasury bill or money market fund pays interest, and that interest is taxable in the year you receive it whether you spend it or reinvest it. BOXX doesn’t hold Treasuries or any interest-paying debt. It builds a synthetic short-term return using offsetting options positions (box spreads) whose payoff tracks what a 1-to-3-month T-bill would pay. Those gains stay embedded in the share price as unrealized appreciation instead of being paid out.
The fund structures its positions as straddles under Section 1092 of the tax code, which prevents gain recognition on one leg while an offsetting loss remains unrealized on the other. Combined with the ETF wrapper’s ability to move appreciated securities out in-kind without triggering taxable events for remaining holders, the result is a fund that accumulates value internally and passes nothing through to shareholders each year. If you hold BOXX for five years without selling, you owe zero federal income tax on it during those five years.
The Rate You Pay When You Sell
Selling is the taxable event, and your holding period sets the rate.
Shares held longer than one year qualify for long-term capital gains rates of 0%, 15%, or 20%. For 2026, the 20% rate begins at $545,500 of taxable income for single filers and $613,700 for joint filers. Most investors fall into the 15% bracket or below.
Shares sold within a year are taxed at short-term capital gains rates, which mirror ordinary income brackets and reach 37%.1Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026 At that point, the tax advantage over a money market fund largely disappears. BOXX works as a tax strategy only if you plan to hold at least twelve months.
The 3.8% Surtax for Higher Earners
Capital gains from selling BOXX count as net investment income, so the 3.8% Net Investment Income Tax applies once modified adjusted gross income exceeds $200,000 for single filers or $250,000 for joint filers.2Office of the Law Revision Counsel. 26 U.S.C. 1411 – Imposition of Tax Those thresholds are not indexed to inflation, so more filers cross them each year. An investor in the top long-term bracket who also owes NIIT pays an effective 23.8% on BOXX gains. That’s still well below the 40.8% combined rate on ordinary interest at the same income level, but the spread is smaller than the headline 20% vs. 37% comparison suggests.
BOXX vs. Treasuries: What You Give Up
Direct Treasury bill interest is taxed at ordinary federal rates but is exempt from state and local income tax.3TreasuryDirect. Treasury Bills BOXX inverts the equation: you may pay a lower federal rate through long-term capital gains treatment, but your gains are fully taxable at the state level.
In a no-income-tax state, and assuming you hold longer than a year, BOXX almost always wins after tax. In a high-tax state the answer isn’t obvious. A New York City resident, for example, forfeits a combined state and city exemption on Treasury interest that can top 12%, in exchange for federal capital gains treatment. Whether that’s a net win depends on your federal bracket, how long you defer the sale, and whether NIIT applies.
There’s also a fee to account for. BOXX charges a net expense ratio of 0.1949%.4Alpha Architect. Alpha Architect 1-3 Month Box ETF Treasuries bought directly through TreasuryDirect carry no management fee. When short-term yields are around 5%, a 0.19% drag is minor. When yields fall closer to 2%, that same fee eats close to a tenth of the gross return, and the tax advantage has less absolute yield to work with.
The Section 1258 Risk
The most important caveat isn’t about rates. It’s about whether BOXX’s tax treatment survives IRS scrutiny.
Section 1258 lets the IRS recharacterize capital gain as ordinary income when substantially all of the taxpayer’s expected return comes from the time value of money in a hedged position.5Office of the Law Revision Counsel. 26 U.S. Code 1258 – Recharacterization of Gain From Certain Financial Transactions A box spread earns exactly the risk-free rate through exactly the time value of money in exactly a hedged position. The statute lists four categories of covered transactions, including straddles and transactions marketed as producing capital gains from time-value returns. Box spreads arguably fit more than one.
BOXX’s own prospectus acknowledges this: if the IRS treated the transactions as conversion transactions under Section 1258, gains could be recharacterized as ordinary income.6Alpha Architect. Alpha Architect 1-3 Month Box ETF Prospectus The fund’s position is that Section 1258 applies at the fund level rather than the shareholder level, and that a shareholder’s gain arises from selling an ETF share on the open market, not from closing a conversion transaction.
As of mid-2026, the IRS has not challenged BOXX or issued guidance targeting box spread ETFs, and the 2025-2026 Priority Guidance Plan does not list the issue.7Internal Revenue Service. 2025-2026 Priority Guidance Plan Silence is not approval. A future ruling could apply to open tax years, which would mean gains you’ve already realized get recharacterized after the fact.
Reporting When You Sell
If you don’t sell during the year, you have nothing to report. No 1099-DIV, no K-1, no entries on Schedule D.
When you do sell, your broker issues a Form 1099-B showing proceeds and cost basis. You carry those figures to Schedule D of Form 1040, using Form 8949 if adjustments are needed. Confirm the holding period printed on the 1099-B against your purchase dates, especially if you bought shares in multiple lots. A lot mistakenly flagged short-term can cost you the entire point of holding BOXX in the first place.
If you underreport or misclassify, the failure-to-pay penalty runs at 0.5% of the unpaid tax per month, capped at 25%, and interest on the underpayment accrues separately on top of that penalty.8Internal Revenue Service. Failure to Pay Penalty Getting basis and holding period right at the sale is cheaper than fixing it later.