OID is the difference between the amount an investor pays for a Zero-Coupon CMBS, and the face amount an investor later receives is known as "imputed interest." This is interest that the Internal Revenue Service (IRS) considers to have been paid, even if an investor haven't actually received it. Therefore, the IRS requires that an investor pay tax on this "phantom" income each year, just as an investor would pay tax on interest an investor received from a coupon bond.
INVESTMENTS IN SECURITIES INVOLVE RISK OF LOSS THAT INVESTORS MUST BE PREPARED TO BEAR.