William Thomas O'Connor, M.D.
Family Medicine Physician · Vacaville, CA
William Thomas O'Connor, M.D. is a family medicine physician with a practice address in Vacaville, California, and NPI 1639127632, issued on May 4, 2006. Check the license (California G048496, as entered in NPPES) on the Medical Board of California; the Medicare figures below come from public CMS files.
- Name
- William Thomas O'Connor
- Credential
- M.D.
- Primary taxonomy
- Family Medicine Physician 207Q00000X
- License number
- G048496 CA
Self-reported in NPPES; status is on the state search - Practice location
- 300 Mason St., Vacaville, CA 95688
- Phone
- (707) 446-0422
- Enumerated
- May 4, 2006
- Record last updated
- Dec 9, 2014 (not updated in 12 years: call before relying on the address or phone)
- Fax
- (707) 446-1655
- Medicaid ID
- 00G484960 CA
- Medicare enrollment
- Enrolled (PECOS I20110721000073); accepts Medicare assignment
- Medical or professional school
- University Of Cincinnati College Of Medicine, 1981
- Telehealth
- Offers telehealth (CMS)
- Entity
- Type 1 · individual
8 nearest family medicine physician records → All 17,133 in California → Look up another NPI →
Verify William Thomas O'Connor in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersMedical Board of California
Search for license G048496Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
43% fewer Medicare Part D claims than the average family medicine physician in 2024
2,018 Medicare Part D claims for 113 beneficiaries, against an average of 3,544 among the 117,163 providers of this specialty who prescribed in Part D. 21 claims were for opioids.
Most prescribed
- Rosuvastatin Calcium134 claims
- Metoprolol Succinate117 claims
- Metformin Hcl97 claims
- Levothyroxine Sodium96 claims
- Atorvastatin Calcium89 claims
- Lisinopril65 claims
Source: CMS Medicare Part D Prescribers by Provider and Drug, 2024 (data.cms.gov). Part D covers prescriptions for Medicare patients only; drugs with fewer than 11 claims are not published.
Industry payments in 2024: $628.59
14 payments; by number, the most common kind was food and beverage; the largest payer was Boehringer Ingelheim Pharmaceuticals, Inc. The 55,478 providers of this specialty with any payment received $902.55 on average. Payments are reported by manufacturers, not by the provider, and are not a sign of wrongdoing.
Source: CMS Open Payments, program year 2024 (openpaymentsdata.cms.gov); average among providers of this specialty with at least one payment.
William Thomas O'Connor among 17,133 family medicine physician records in California
William Thomas O'Connor, M.D. is one of 17,133 family medicine physician records with a practice address in California. 81% of them appear in a Medicare file (Part D prescribing, MIPS, Open Payments or Medicare group billing); this one does. Its NPI, issued in 2006, is newer than 6% of them.
- NPI issued2006 · 6% of these records are older, 59% newer
- In a Medicare fileYes · 81% of these records are
- In the CMS Doctors and Clinicians fileYes · 62% of these records are
- Graduated1981 · median 2005 among the 10,652 with a school on file
- Record last updated2014 · 58% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 207Q00000X and a California practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
56 family medicine physician records list a practice address in Vacaville
They are 56 of the 1,903 NPPES records with a practice address in Vacaville, and 17,133 family medicine physician records in California.
All 17,133 in California → Every provider in Vacaville → Family Medicine Physician nationwide →
The 8 family medicine physician records with the nearest ZIP codes
- Azim Ahmady, MDVacaville, CA 956881417035916
- Teresa Auyeung, MDVacaville, CA 956881780771154
- Raquel Cripe, M.D.Vacaville, CA 956881912922782
- Ricardo Denapoli, D.O.Vacaville, CA 956881295703189
- Peaslee Dumont, MDVacaville, CA 956881588748768
- Michael Earwood, MDVacaville, CA 956881932287828
- Gail Feinberg, DOVacaville, CA 956881194760025
- Behroz Hamkar, M.D.Vacaville, CA 956881073525036
Common questions
What is William Thomas O'Connor, M.D.'s NPI number?
William Thomas O'Connor, M.D.'s National Provider Identifier (NPI) is 1639127632, issued on May 4, 2006. An NPI identifies a provider in billing; it is not a license.
Where is William Thomas O'Connor, M.D. located?
The NPPES record lists a practice address at 300 Mason St., Vacaville, CA, 95688. Phone: (707) 446-0422. Providers update this record themselves, so call before visiting.
How can I verify William Thomas O'Connor, M.D.'s license?
NPPES lists California license number G048496, as entered by the provider. Search the Medical Board of California at https://www.mbc.ca.gov/License-Verification/default.aspx. The NPPES record confirms identity only; the state search shows license status, expiration and public orders.
How much does William Thomas O'Connor, M.D. prescribe under Medicare Part D?
In 2024, William Thomas O'Connor, M.D. had 2,018 Medicare Part D claims for 113 beneficiaries; the average among family medicine physician prescribers was 3,544. Part D covers Medicare prescriptions only.
Source: CMS National Plan and Provider Enumeration System (NPPES), file of Aug 9, 2026 (NPPES files on CMS.gov); NUCC Health Care Provider Taxonomy. Medicare files from data.cms.gov. An NPI identifies who bills; it is not a license.
Figures on PlainDoctor are read from the federal files each page names (CMS NPPES, Medicare Part D, MIPS, Open Payments; the HHS-OIG exclusion list only as counts) and from Census population estimates, with the file date shown beside them. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of Aug 9, 2026.