Definition
Per CGC's own glossary, a comic book that is 'missing a coupon' — i.e., a subscription or promotional coupon printed on an interior or cover page has been physically cut or torn out. This is treated as a defect that detracts from a copy's condition and completeness relative to an otherwise identical copy with its coupon intact.
In Panel Profits
Panel Profits treats a verified coupon-clipped copy as trading at a discount to a comparable copy of the same numeric grade with its coupon intact, since the missing coupon is a permanent, non-restorable completeness defect that a numeric grade alone does not fully communicate.
Comic-market example
Two copies of the same Bronze Age issue both certify at 7.0, but one has had its house-ad coupon clipped. All else equal, the coupon-clipped copy should be expected to clear at a discount to the intact copy, because coupon-clipping is a documented, permanent defect rather than a cosmetic difference the grade alone captures.
Common mistakes
Do not assume a numeric grade alone captures coupon completeness — two copies at an identical grade are not necessarily comparable if one is coupon-clipped. Do not treat coupon-clipping as restorable; a clipped coupon cannot be un-clipped without being flagged as restoration/piece-fill work.