# CMS Anesthesia Base Units (00100-01999)

`medicare_silver.dim_anesthesia_base_unit` · Medicare Advantage, Part D, Medicaid · status live · 1,933 rows

The standalone CMS Anesthesia Base Units schedule (Anesthesiologists Center ZIPs). Base units are the fixed leg of Medicare anesthesia payment: payment = (base_units + time_units) x anesthesia_conversion_factor. SEPARATE schedule - never in the PFS PPRRVU RVU file (those anesthesia rows carry status indicator J, RVU=0). A code absent from this table is 'not anesthesia-priced', not $0. Qualifying-circumstance codes (99100/99116/99135/99140) are NOT in the CMS file. calendar_year is the CMS PUBLICATION year; CMS republishes only in change years and states values are 'unchanged for CY 20xx' otherwise, so each vintage GOVERNS every service year until the next published file (encoded in effective_period_start/end): CY2014 governs 2014-2017, CY2018 governs 2018-2021, CY2022 governs 2022 onward.

**Grain.** One row per (hcpcs_code, calendar_year) - the integer anesthesia base-unit count for each anesthesia CPT code, per CMS publication year.

| column | type | meaning |
|---|---|---|
| hcpcs_code | string |  |
| calendar_year | int |  |
| base_unit | int |  |
| observed_period | date |  |
| asserted_at | date |  |
| effective_period_start | date |  |
| effective_period_end | date |  |
| cms_vintage_sequence | int |  |
| parse_revision | int |  |
| parser_artifact_hash | string |  |
| source_url | string |  |
| sha256_content_hash | string |  |
| source_id | string |  |
| is_current | boolean |  |
| bronze_object_key | string |  |
| s3_version_id | string |  |
| vintage_tag | string |  |
| drug_source_version_id | string |  |

Query it: `query_substrate` with `SELECT ... FROM medicare_silver.dim_anesthesia_base_unit WHERE ... LIMIT 100`; read `describe_data_source("medicare_silver.dim_anesthesia_base_unit")` first.