Provider records sourced from NPPES (CMS National Plan & Provider Enumeration System). Data current as of October 4, 2026.
NPIDirectory

William Thomas Halsey, MD

Individual provider Anesthesiology Physician · NPI 1295775237

William Thomas Halsey, MD is an Anesthesiology Physician in San Francisco, California. Licensed in California. Registered with an NPI since 2006.

Licensed in
CA
In the registry since
2006
Specialties on file
2
What do these letters mean?
MD — Doctor of Medicine
A physician who completed allopathic medical school.

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Practice location Address checks out

3700 California St
San Francisco, CA 94118-1618 Not confirmed with CMS for 19 years — call before visiting
Phone: (415) 719-0000
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Pin is approximate — placed at the ZIP-code centre, not the exact door.

Specialties & licences

Anesthesiology Physician (primary) Taxonomy 207L00000X · Licence C37471 (CA)
Pain Medicine (Anesthesiology) Physician Taxonomy 207LP2900X · Licence C37471 (CA)

Record details

NPI number1295775237
Entity typeIndividual (Type 1)
GenderMale
Credentials MD
Sole proprietorNo
NPI enumeratedJune 7, 2006
Last updated in NPPESJuly 11, 2007

Medicare patients and services, 2024

From the CMS Medicare Physician & Other Practitioners file for calendar year 2024. It counts Original Medicare patients only, so a practice that mostly sees Medicare Advantage or privately insured patients looks smaller here than it is.

Medicare patients76
Services billed 123 a service is one billed item, such as a visit, a test or a procedure
Average patient age70

Dollar amounts are not shown. What Medicare pays a practice is gross billings, before staff, premises and tax and including the cost of any drugs it administers, so it is not what a clinician earns.

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