Billing and Coding: MolDX: Testing of Multiple Genes

Genetic testing panels (2+ genes assayed in parallel for the same indication) must be billed as a single procedural service with the appropriate HCPCS/CPT and z-code and are covered when the panel is reasonable and necessary for the beneficiary per CFR §410.32. Serial or reflex testing where one gene’s result determines subsequent testing may be billed as individual gene services if each is reasonable and necessary; multiple distinct services on the same date generally should not exceed two without attestation, and modifier 59 must be used to attest that additional billed services are distinct procedural services. Laboratories must register tests with the Diagnostics Exchange, document clinical use/medical necessity in the record, and use correct billing codes; inappropriate billing of parallel assays as separate tests or excessive use of modifier 59 may trigger medical review.

"A set of 2 or more genes assayed in parallel for the same clinical indication (results of one assay do not affect the decision to complete the other assays) is a single panel procedural service and..."