Effective January 1st, 2021, CMS has replaced add-on code HCPCS CPT G2058 with the add-on code CPT 99439. CPT 99439 can now be bill concurrently with TCM, when reasonably necessary.
The 2021 Physician Fee Schedule (PFS) Final Rule states that the CPT 99439 descriptor is identical to CPT G2058.
CPT Code 99439 Descriptor:
Chronic care management services, each additional 20 minutes of clinical staff time directed by a physician or other qualified health care professional, per calendar month
CPT 99439 is billed for an additional 20-minutes of service after the initial 20 minutes billed as CPT 99490. Providers are allowed to bill two (2) CPT 99439 codes with CPT 99490 in a calendar month.