Tax Implications of Taxable Debt Securities

With yield, pricing, and credit quality covered, the final piece of the return puzzle is taxes. How much of your bond return you actually keep depends on the tax treatment of the interest, any original issue discount, market discount, and premium.

Interest Income

The basic tax treatment of bond interest depends on who issued the bond:

• Coupon interest on corporate bonds is taxable as ordinary income at all levels (federal, state, local)
• U.S. Treasury interest is taxable at the federal level but exempt from state and local taxes
• Most agency securities are fully taxable - they are NOT government-issued despite the government connection

Exam Tip: Gotchas

Fannie Mae, Freddie Mac, and Ginnie Mae interest is fully taxable at all levels. Only a few specific agencies (Farm Credit, Federal Home Loan Bank, certain TVA securities) share the Treasury's state/local tax exemption. Not all agency interest is state-tax exempt.

Original Issue Discount (OID)

OID arises when a bond is issued at a price below par. The discount is treated as additional interest, not a capital gain.

• The discount is accreted (recognized) annually over the life of the bond using the constant yield method
• OID accretion is taxed as ordinary income each year, even though no cash is received until maturity
• The investor's cost basis increases each year by the amount of OID accreted
• At maturity, the adjusted basis equals par, so there is no capital gain or loss
• The constant yield method results in increasing amounts recognized each year (not straight-line)

Zero-Coupon Bonds: The Purest Form of OID

• A zero-coupon bond purchased at issue for $600 with $1,000 par: the $400 discount is OID accreted annually
• The entire return on a zero-coupon bond is OID; there is no coupon payment
• This creates "phantom income"; the investor owes taxes each year without receiving any cash

Think of it this way: You bought a bond for $600 that will pay $1,000 at maturity. The IRS says you are "earning" part of that $400 discount every year, so you owe tax on it annually, even though you will not see a dime until the bond matures. That is why zero-coupon bonds work best inside tax-deferred accounts like IRAs.

Exam Tip: Gotchas

OID creates phantom income; you owe taxes on imputed interest each year without receiving any cash. This makes zero-coupon bonds particularly unsuitable for taxable accounts and better suited for tax-deferred accounts (IRAs, qualified plans).

Market Discount

Market discount is different from OID. It arises when a bond is purchased in the secondary market at a price below par (or below the adjusted OID issue price).

• If the bond is held to maturity, the market discount is taxed as ordinary income (not capital gain)
• If sold before maturity, the gain up to the amount of accrued market discount is ordinary income; any excess gain is capital gain
• The investor may elect to include market discount in income annually (on a constant yield or straight-line basis) rather than deferring to maturity

Exam Tip: Gotchas

Market discount at maturity is taxed as ordinary income, NOT capital gain. Students often assume that buying a bond below par and receiving par at maturity produces a capital gain, but the IRS treats this discount as deferred interest income.

Bond Premium

A bond purchased above par has a premium. The tax treatment depends on whether the bond is taxable or tax-exempt.

Taxable Bonds (Elective Amortization)

• The investor may elect to amortize the premium over the remaining term
• Amortization reduces the amount of interest income reported each year
• Amortization also reduces the investor's cost basis in the bond
• If amortized to maturity, the adjusted basis equals par - no capital loss at maturity
• If the investor does not elect to amortize:
  • The full coupon is taxable as interest each year
  • A capital loss is recognized at maturity (or sale) when par is received but a higher price was paid

Tax-Exempt Bonds (Mandatory Amortization)

• For municipal bonds, premium amortization is mandatory (required, not elective)
• The amortized premium cannot be used to reduce taxable income (since the interest is already tax-exempt)
• Cost basis is still reduced each year by the amortization amount

Exam Tip: Gotchas

Premium amortization is ELECTIVE for taxable bonds but MANDATORY for tax-exempt (municipal) bonds. Also, amortizing premium on a taxable bond reduces both reported interest income AND cost basis; the investor does NOT get to take a capital loss at maturity if they amortize.

Capital Gains and Losses on Bonds

• A bond sold before maturity at a price above the adjusted cost basis generates a capital gain
• A bond sold before maturity at a price below the adjusted cost basis generates a capital loss
• Holding period determines treatment:
  • 1 year or less = short-term capital gain/loss (taxed as ordinary income)
  • More than 1 year = long-term capital gain/loss (preferential tax rates)
• For OID bonds: the capital gain/loss is calculated on the adjusted basis (original price + accreted OID), not the original purchase price

Exam Tip: Gotchas

For OID bonds, always use the adjusted basis (original price + accreted OID) when calculating capital gains or losses. Using the original purchase price is a common error that produces the wrong answer.