Skip to main content
Common Bond Mistakes

Buying Zeros Without Tax Plan

Pomegra Learn

Buying Zeros Without Tax Plan

Zero-coupon bonds and Treasury STRIPS offer attractive discounts (buy at $50 for $100 par), but they create phantom income: taxes are owed annually on the accrued gain, even though you receive no cash. In taxable accounts, they're a tax disaster. In tax-deferred accounts (IRAs, 401(k)s), they're ideal.

Key takeaways​

  • Zero-coupon bonds accrete in value annually (you owe tax on the accrual) but pay no coupon. A $50 zero coupon bond accreting at 5% is worth $52.50 next year, and you owe tax on the $2.50 gain even though you received zero dollars.
  • Treasury STRIPS (Separate Trading of Registered Interest and Principal of Securities) are zero-coupon instruments created by dealers; they're taxed identically to regular zeros and belong only in tax-deferred accounts.
  • A zero-coupon bond held in a taxable account is a "negative cash-flow" investment: you pay taxes from other income while the bond accretes untouched, creating an internal rate of return lower than the promised yield.
  • The same zero coupon bond in a Roth IRA or traditional IRA is ideal: no annual tax drag, and the full accreted value grows tax-free (in Roth) or tax-deferred (in traditional).
  • Investors often use zeros for target-date laddering (a zero maturing in 20 years to pay for college) without realizing they've created an annual tax liability.

Phantom income mechanics​

A zero-coupon bond pays no coupons; instead, it's sold at a steep discount and redeems at par. For example, a 20-year Treasury STRIP might be purchased for $250 and redeemed for $1,000 in 20 years. The $750 gain is the compensation for locking up your money.

The problem: that $750 gain is not deferred to maturity. It's taxed annually as if you'd earned phantom income.

Here's the math. Assume a zero-coupon bond is purchased for $500 and promises to redeem for $1,000 in 10 years. The yield-to-maturity is 7.18% annually. In the IRS's eyes, you've earned:

  • Year 1: $500 × 0.0718 = $35.90 (taxed at your marginal rate)
  • Year 2: $535.90 × 0.0718 = $38.48 (taxed on the accreted value)
  • Year 3: $574.38 × 0.0718 = $41.24
  • ...and so on.

After 10 years, you will have received $0 in cash but will have reported $500 in taxable income (the original $500 gain). At a 24% federal tax rate (plus state and FICA), you've paid roughly $120–150 in taxes over the 10 years on income you never received.

When the bond matures and you receive $1,000, you get $1,000 cash. But you've already paid the taxes, drawn from other accounts. The after-tax return is 5–5.5% (net of taxes), not the promised 7.18%.

Why this matters: the IRR trap​

Most zero-coupon investors buy them for a specific goal: "I need $100,000 in 15 years for college." So they calculate the required principal today: using a 5% yield, they need to invest $48,100 today in a zero-coupon bond.

What they miss: if that $48,100 is in a taxable account, the annual phantom income taxes reduce the effective yield. The real after-tax IRR might be 3.8–4.0%, not 5%. To hit the $100,000 target, they'd actually need to invest $54,000–56,000, not $48,100. And many investors don't realize this gap until it's too late, discovering in year 10 that they're $10,000 short.

The mistake is especially painful for high-income earners in high tax brackets. An investor in the 35% federal + 5% state bracket is paying 40% tax on phantom income. A 5% zero-coupon yield becomes a 3% after-tax yield. The difference compounds over decades.

Treasury STRIPS: same mechanics, higher complexity​

Treasury STRIPS are synthetic zero-coupon instruments created by dividing Treasury securities into separate principal and coupon components. Each component is a zero that trades independently. A 10-year Treasury note might be split into 20 zero-coupon components (one for each 6-month coupon, plus one for principal).

STRIPS are taxed identically to regular zero-coupon bonds: the annual accretion is taxed each year, even though no cash is received. They're issued by the US Treasury and are extremely safe, but the tax treatment is no more favorable than private zero-coupon bonds.

Investors often buy STRIPS for long-dated target-date laddering—a STRIP maturing in 2040 to cover some future liability. But again, if held in a taxable account, the annual phantom income is a drag.

The tax-deferred magic​

Now flip the scenario: the same zero-coupon bond held in a Roth IRA.

The $500 investment grows to $1,000 in 10 years. You pay no taxes annually on the phantom income. The entire $500 gain accrues tax-free. When you withdraw from the Roth at age 59.5 (or earlier under certain conditions), the full $1,000 comes out tax-free.

The after-tax return is 7.18%, exactly the promised yield. The math is clean.

For a traditional IRA, it's slightly different: you still pay no taxes on the phantom income during the accumulation phase. The $500 gain accrues and compounds undisturbed. When you withdraw at retirement, you pay taxes on the entire withdrawal ($1,000 is ordinary income), but you get a one-time tax at your then-current rate, not annual phantom-income taxes.

The traditional IRA is less ideal than Roth (because withdrawals are taxed), but still far superior to taxable-account zeros. A traditional IRA zero-coupon bond effectively gives you 10 years of tax deferral, which is valuable.

Why zeros are ideal for IRA ladder strategies​

Zero-coupon bonds (or STRIPS) are particularly useful in IRAs for a strategy called "bond-ladder targeting": you buy zeros maturing in years 1, 2, 3, ..., 20 to create a predictable cash flow for retirement.

Example: a 65-year-old is retiring and needs $50,000 annually for 20 years (plus Social Security). They can build a 20-rung ladder of STRIPS in a traditional IRA:

  • Buy a 1-year STRIP for ~$47,600 (yields 5%, redeems $50,000)
  • Buy a 2-year STRIP for ~$45,400 (yields 5%, redeems $50,000)
  • Buy a 3-year STRIP for ~$43,350 (yields 5%, redeems $50,000)
  • ...and so on up to 20 years.

Total investment: ~$673,000. In 20 years, the IRA will have paid out exactly $50,000 × 20 = $1M (plus the accumulated phantom income taxes are deferred, then paid all at once on withdrawal).

This strategy is nearly impossible in a taxable account because of the annual phantom income drag. But in an IRA, it's elegant and effective.

The muni zero trap​

A subspecies of the zero problem occurs with municipal zero-coupon bonds. These are issued by states and municipalities, and the coupon is exempt from federal (and sometimes state) income tax.

A muni zero still creates phantom income, but the phantom income is federal-tax-exempt (in theory). An investor in a high tax bracket might be tempted to buy a muni zero in a taxable account, thinking: "The phantom income is tax-free, so I'm not paying annual taxes!"

This logic is partially correct but potentially dangerous. The phantom income is tax-exempt for federal purposes, but:

  1. It's not exempt from FICA or state taxes. Some states tax muni income; the phantom income is included in the calculation.
  2. It triggers AMT (Alternative Minimum Tax) for some investors. High-income earners subject to AMT find that muni phantom income is not AMT-exempt, creating a surprise tax liability.
  3. It's still phantom income. You're still accruing value you don't receive in cash, creating the same IRR trap as Treasury zeros.

The rule: zeros belong in tax-deferred accounts. If you want yield-efficient instruments for a taxable account, use coupon-paying bonds (which have well-understood tax treatment) or Treasury Inflation-Protected Securities (TIPS, which have their own tax complications but are more standard).

Identifying zeros in your portfolio​

If you've bought bonds without carefully tracking the tax implications, you might unknowingly hold zeros.

  • Direct ownership: Look for bonds labeled "zero-coupon," "STRIPS," or sometimes "accrual bonds." If the prospectus says "no coupon," it's a zero.
  • Fund holdings: Most bond funds (BND, AGG, VBTLX) don't hold significant zeros. But if you've bought a specialized fund like a "TIPS fund" or "Treasury fund," check the fact sheet to see if any STRIPS are included.
  • 529 plans: Some 529 college savings plans recommend buying zeros to match future tuition dates. If you have a 529, check whether it holds zeros in a taxable or a qualified account. (They're usually held in a UTMA/UGMA taxable account, which is a mistake.)

Process: audit and reposition zeros​

If you find zeros in a taxable account:

  1. Calculate the damage. Use the bond's yield-to-maturity to estimate annual phantom income. Multiple by your tax rate to get the after-tax drag.
  2. Check how long you'll hold. If you plan to hold the zero to maturity, the tax drag is locked in. If you might sell earlier, you face capital-gains tax too.
  3. Decide on repositioning. If the zero is substantially underwater (higher yields available today), sell it, realize the loss, and use the proceeds for a coupon-paying bond or a zero in a tax-deferred account. If the zero is close to par or yielding well, you might hold it and avoid realizing losses. New zeros should never go into taxable accounts.

For zeros already in IRAs or 401(k)s: hold them as planned. They're ideal there.

Flowchart: is a zero-coupon bond right for you?​

Next​

You've now seen how tax efficiency can make or break bond returns, and how the account type (taxable vs. tax-deferred) drives strategy. Next, we'll explore a macro-level mistake: failing to rebalance your bond allocation as time passes and market movements accumulate.