Zero Coupon Municipal Bonds: Tax Treatment

I have been trying to determine whether zero-coupon municipal bonds are subject to market discount rules for taxation purposes. In short, is the buyer of a zero-coupon muni held to maturity ever subject to federal taxes (other than the alternative minimum tax)?

-- William Duke

William,

Ah, tax time.

In short, yes, buyers of zero-coupon municipal bonds may incur a tax liability, but that liability does not have to be recognized until the bond is redeemed or sold.

Before I go on, let me explain your question to other readers.

The question concerns tax-exempt zero-coupon municipal bonds.

A regular bond pays interest on its face value, or principal, twice a year at a rate determined by its coupon. A bond with a face value of $1,000 and a 6% coupon pays $60 a year in two installments until it matures and the principal is returned. Most coupon-bearing bonds are originally sold at face value.

Zero-coupon bonds don't have coupons, so they don't make annual interest payments. Instead, they are originally sold at a steep discount to face value, also known as an OID (original issue discount). For example, a bond with a face value of $1,000 may be sold for $500. So while zero-coupon bonds don't make interest payments, they do offer an interest rate that is a function of the difference between the purchase price and face value, and the time remaining until maturity. For example, a 10-year zero-coupon bond sold at a price of 50 (or $500 for a $1,000 bond) offers an interest rate, or yield, of 7.05%.

As explained to me by Michael Decker of the Bond Market Association, the tax rules for zero-coupon bonds bought as new issues and held to maturity are fairly simple.

Whether the bond is taxable or tax exempt, you have to accrue interest on the bond. That means you have to calculate the portion of the difference between the purchase price and face value that accrued to you each tax year, even though you didn't receive any payment. The interest accrues at the interest rate you obtained when you bought the bond. Using the earlier example, if you paid $500 for a 10-year, $1,000 bond getting an interest rate of 7.05%, you would accrue $35.25 of interest in the first year.

$500 x 0.0705 = $35.25

Your adjusted issue price, or cost basis, in the bond, would then become $535.25.

$500 + $35.25 = $535.25

The following year, you would accrue $37.74 of interest.

$535.25 x 0.0705 = $37.74

And so on.