Quick answers
- Does Oliver L. Mason accept Medicare assignment?
- Yes. Medicare's clinician data says Oliver L. Mason accepts Medicare assignment (the Medicare-approved amount as full payment for covered services), as of October 2, 2026. Ask the office to confirm before your visit.
- How many Medicare patients does Oliver L. Mason see?
- In 2024, CMS data shows 114 Original Medicare patients and 323 services for Oliver L. Mason. This counts Original Medicare only and measures volume, not quality.
- What is Oliver L. Mason's NPI number?
- 1871606434. The NPI (National Provider Identifier) is the clinician's permanent federal ID; you can look it up in the official NPI Registry.
Medicare activity in 2024
Official CMS public-use data for Oliver L. Mason, data year 2024 (released May 21, 2026). It covers Original Medicare (fee-for-service) patients only, not Medicare Advantage or other insurance. It shows volume, not quality or outcomes. CMS hides any count of 10 or fewer patients.
| Original Medicare patients | 114 |
|---|---|
| Services billed to Medicare | 323 |
| Different services or procedures | 5 |
| Participating Medicare provider | Yes |
| Average age of these patients | 50 |
Most frequent services
- Subsequent hospital care with moderate levelof medical decision making, if using time, at least 35 minutes (99232)140 services
- Subsequent hospital care with straightforward or low level of medical decision making, per day, if using time, at least 25 minutes (99231)103 services
- Initial hospital care with moderate level of medical decision making, if using time, at least 75 minutes (99223)72 services
Chronic conditions among these patients
Share of this clinician’s Original Medicare patients with each condition, as published by CMS (it describes the patients, not the care given).
- Depression75%
- Anxiety75%
- High cholesterol67%
- High blood pressure63%
- Arthritis39%
- Diabetes34%
Practice locations
Addresses where Oliver L. Mason is enrolled with Medicare (CMS data updated October 2, 2026).
- 2776 Pacific AveLong Beach, CA 90806 (562) 999‑2000
Specialties
- Internal Medicineprimary
Other internal medicine doctors in Long Beach
Clinicians with the same Medicare primary specialty in Long Beach, CA — not a recommendation.
Clinician information
| Credential | MD |
|---|---|
| Medical school | University Of California, San Francisco School Of Medicine |
| Graduation year | 1984 (42 years since medical school) |
| Gender (as listed) | Male |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| NPI (National Provider Identifier) | 1871606434 |
| Corrections | Report an error or suggest an update → |
Most corrections must be made at the source: clinicians update their NPI Registry record (NPPES) and their Medicare enrollment (PECOS); this page follows the next data release.
Sources
- National Downloadable File (Doctors and Clinicians) — CMS, data updated October 2, 2026, retrieved October 29, 2026
- Medicare Physician & Other Practitioners - by Provider — CMS, data year 2024, released May 21, 2026; Medicare Physician & Other Practitioners - by Provider and Service
- NPI Registry — U.S. Department of Health and Human Services (NPPES), the clinician’s official record
- Medicare Care Compare — official Medicare tool to look up clinicians