Tax Treatment of Bond Premium and Discount Amortization

You buy a corporate bond for $1,050 that matures at $1,000 in five years. At maturity, you receive $1,000 — $50 less than you paid. Without understanding bond premium amortization, you might report a $50 capital loss. The IRS sees it differently: the $50 premium should have been amortized annually over the bond's life, reducing your taxable interest income each year. If you didn't amortize, you've been overpaying taxes on interest income for five years, and you may not be able to claim the full loss at maturity.

TL;DR: When you buy a bond above par (premium) or below par (discount), the IRS requires specific tax treatment for the difference. Bond premium on taxable bonds can be amortized to reduce interest income — and for tax-exempt bonds, amortization is mandatory. Original issue discount (OID) must be included in income annually as it accrues, even though you don't receive the cash until maturity. Market discount is generally recognized at sale or maturity.

Bond Premium: Buying Above Par

A bond trades at a premium when its market price exceeds its face value (par). This happens when the bond's coupon rate is higher than prevailing interest rates — investors pay extra for the above-market income stream.

Taxable Bond Premium

When you buy a taxable bond at a premium, you have two options:

Option 1: Amortize the Premium (Election Under §171)

You can elect to amortize the premium over the remaining life of the bond, reducing your taxable interest income each year. The amortization is calculated using the constant yield method (essentially, the effective interest rate method).

Example:

• Bond purchased at $1,050, par value $1,000, 5% coupon, 5 years to maturity
• Annual coupon: $50
• Annual premium amortization: approximately $10/year (simplified — actual constant yield calculation varies slightly)
• Taxable interest income: $50 - $10 = $40/year instead of $50
• Your basis decreases by $10/year: $1,050 → $1,040 → $1,030 → $1,020 → $1,010 → $1,000 at maturity

Why this matters: amortizing saves you from paying tax on income that's really a return of your own premium. At a 37% marginal rate, amortizing $10/year saves $3.70/year — modest per bond, but material across a bond portfolio.

Option 2: Don't Amortize

If you don't elect to amortize, you report the full coupon as interest income each year. At maturity (or sale), the $50 premium becomes a capital loss. However, this capital loss is subject to the capital loss deduction limits ($3,000/year against ordinary income) and can only offset capital gains dollar-for-dollar.

The point is: amortization converts what would be a capital loss into a reduction of ordinary income — which is almost always more valuable. Once you elect to amortize taxable bond premium, the election applies to all taxable bonds you own and future acquisitions. It's generally the right choice.

KEY INSIGHT: Most bond investors should elect to amortize premium under §171. Converting the premium from a capital loss to an ordinary income reduction is tax-advantaged in virtually every scenario. Once elected, it applies to all taxable bonds going forward.

Tax-Exempt Bond Premium (Mandatory Amortization)

For tax-exempt municipal bonds purchased at a premium, amortization is mandatory — there's no election. You must reduce your basis by the amortized premium amount each year. Since the interest is tax-exempt, you don't get an income reduction — the amortization simply reduces your basis.

At maturity, your basis should equal par value ($1,000), and there's no gain or loss. If you sell before maturity, your adjusted basis (reduced by amortization) determines your gain or loss.

Original Issue Discount (OID): The Phantom Income Problem

Original Issue Discount occurs when a bond is issued at a price below par. The most common examples are zero-coupon bonds (issued at deep discounts) and bonds issued below par during rising rate environments.

How OID Is Taxed

OID must be included in ordinary income annually as it accrues — even though you receive no cash until the bond matures or pays a coupon. This is often called "phantom income" because you're taxed on income you haven't received.

The annual OID inclusion is calculated using the constant yield method, which front-loads more of the discount into earlier years.

Example (zero-coupon bond):

• Purchase price: $600 (issued at OID)
• Par value: $1,000
• Maturity: 10 years
• Total OID: $400
• Annual OID inclusion: approximately $35-$45/year (increasing each year under constant yield method)
• You owe tax on this income each year despite receiving zero cash

Why this matters: zero-coupon bonds in taxable accounts create a cash flow mismatch — you owe tax annually but receive no interest to pay it with. Zero-coupon bonds are most appropriate for tax-deferred accounts (IRAs, 401ks) where the phantom income isn't taxed currently.

OID Reporting

Your broker reports OID on Form 1099-OID. Box 1 shows the OID for the year, and Box 6 shows the original issue price. You include the OID as interest income on Schedule B.

Your basis increases each year by the amount of OID included in income. At maturity, your basis should equal par value, resulting in no gain or loss.

REMEMBER: OID bonds (especially zero-coupon bonds) create annual taxable income without cash flow. Unless held in a retirement account, the phantom income creates a drag that most investors don't anticipate when they buy the bond.

Market Discount: Buying Below Par in the Secondary Market

Market discount is different from OID. It occurs when you buy an existing bond in the secondary market at a price below its adjusted issue price (which is par for bonds issued at par, or the accreted OID value for OID bonds).

How Market Discount Is Taxed

You have two choices for recognizing market discount:

Option 1: Recognize at Sale or Maturity (Default)

Under the default method, you don't recognize market discount annually. Instead, when you sell or the bond matures, any gain up to the amount of accrued market discount is taxed as ordinary income — not capital gains.

Example:

• Buy a bond for $950 (par $1,000, 5 years to maturity)
• Market discount: $50
• Accrued market discount after 3 years: $30 (using ratable accrual)
• Sell for $980 → gain is $30
• $30 of the gain is ordinary income (accrued market discount), not capital gain

Option 2: Elect Annual Inclusion

You can elect to include market discount in ordinary income annually as it accrues (using either the ratable method or constant yield method). This avoids the surprise of ordinary income at disposition and starts your basis adjustment immediately.

The De Minimis Rule

If the market discount is less than 0.25% of par value × remaining years to maturity, it's considered de minimis and treated as zero. The gain at maturity or sale is capital gain, not ordinary income.

Example: A bond with $1,000 par and 10 years remaining has a de minimis threshold of $25 (0.25% × $1,000 × 10). If you buy it for $980 ($20 discount), the discount is de minimis — any gain at sale is capital gain.

What this means in practice: for bonds purchased just slightly below par, the de minimis rule saves you from ordinary income treatment on small discounts. Always check whether your discount falls below the threshold before assuming it's market discount.

How Brokers Report Premium and Discount

Starting with bonds acquired in 2014 and later (covered securities), brokers are required to track and report premium amortization and OID on your 1099 forms:

For bonds acquired before 2014 (noncovered), you're responsible for tracking premium, OID, and market discount yourself. This is one of the most error-prone areas of bond taxation.

The test: check your 1099-INT for Box 11. If it shows bond premium and your interest income in Box 1 hasn't been reduced, you may need to make the adjustment on your return manually.

Practical Impact on Bond Fund Investors

If you own bond mutual funds or bond ETFs rather than individual bonds, premium and discount mechanics are handled inside the fund. The fund's NAV reflects the amortized premium and accreted discount of its holdings. However:

• Capital gain distributions from bond funds may include gains that are partially ordinary income from market discount
• Return of capital distributions may reflect premium amortization
• OID from zero-coupon bond positions within the fund flows through as ordinary income

Your 1099-DIV from a bond fund captures these adjustments, but the detail is buried in the fund's year-end tax information supplement. Review this document if you hold bond funds with significant premium/discount positions.

Action Checklist

Essential (for individual bond holders)

• Determine if you purchased bonds at a premium or discount — check purchase price versus par value
• Elect premium amortization (§171) for taxable bonds if you haven't already — it's almost always beneficial
• Track OID inclusions if you hold zero-coupon or OID bonds in taxable accounts

High-Impact (reduce tax surprises)

• Hold zero-coupon bonds in retirement accounts to avoid phantom income taxation
• Check the de minimis rule for bonds purchased slightly below par — small discounts may qualify for capital gain treatment
• Review 1099-INT Box 11 to ensure your broker is properly amortizing premium if you elected amortization

Optional (for active bond traders)

• Consider electing annual market discount inclusion if you frequently trade bonds purchased below par
• Model the constant yield vs ratable accrual methods for market discount — constant yield front-loads less income in early years
• Maintain records for pre-2014 bonds that aren't covered by broker basis reporting

Your Next Step

Check your brokerage account for any individual bonds and note their purchase price versus par value. For bonds purchased above par, confirm that premium amortization is active in your account settings (most brokers apply it by default for covered securities). For bonds purchased below par, calculate whether the discount exceeds the de minimis threshold — if it does, the gain at maturity will be ordinary income, not capital gain.