Doctor profile · Federal record
Dr. William Lai, MD
Internal Medicine Physician (CMS: Internal Medicine) · Fontana, CA
- NPI 1528180361
- Accepts Medicare
- 22 yrs in practice
- Male
- Solo practice
- No sanctions
Practice & contact
- Primary practice
-
9961 Sierra Ave
Fontana, CA 923356720
(909) 427-5000
Credentials & registration
- NPI registered
- April 2007 — 19 yrs on file
- Profile last updated
- November 17, 2021
- Year of graduation
- 2004 — 22 yrs since
- Specialty taxonomy
- 207R00000X — NUCC code
- State license (1)
- California #A93123
Federal sanctions & exclusions
No sanctions, exclusions or revocations on file
Checked against OIG LEIE on NPI 1528180361. Last verified May 11, 2026.Medicare procedures · 2023
Top services delivered
Total services
24
Distinct HCPCS
1
Medicare allowed
$2,026
| HCPCS | Description | Services | Patients | Avg allowed | |
|---|---|---|---|---|---|
99221 |
Initial hospital care with straightforward or low level of medical decision making, per day, if using time, at least 40 minutes | 24 | 23 | $84 |
In context: peer comparison
Among 18 peers in Fontana Internal Medicine Physician, average services per provider: 61. This provider delivers 0.4× the peer median.Frequently asked questions
What is Dr. William Lai's medical specialty?
Dr. William Lai practices Internal Medicine Physician in Fontana, CA.
Where does Dr. William Lai practice?
Dr. William Lai practices at 9961 Sierra Ave, Fontana, CA 923356720. Office phone: 9094275000.
What is Dr. William Lai's NPI?
Dr. William Lai's National Provider Identifier (NPI) is 1528180361, issued by NPPES.
Does Dr. William Lai accept Medicare assignment?
Yes. Dr. William Lai accepts Medicare assignment, meaning Medicare-allowed amounts are accepted as full payment for covered services.
What procedures does Dr. William Lai commonly perform?
Top Medicare-reported procedures in 2023: Initial hospital care with straightforward or low level of medical decision making (HCPCS 99221). Source: CMS Medicare Physician & Other Practitioners file.