Joaquin Castillo Marroquin, DO
Emergency Medicine Physician · Corona, CA
Joaquin Castillo Marroquin, DO is an emergency medicine physician with a practice address in Corona, California, and NPI 1316407323, issued on Mar 25, 2019. Check the license (California 202A20916, as entered in NPPES) on the Medical Board of California; the Medicare figures below come from public CMS files.
- Name
- Joaquin Castillo Marroquin
- Credential
- DO
- Primary taxonomy
- Emergency Medicine Physician 207P00000X
- License number
- 202A20916 CA
Self-reported in NPPES; status is on the state search - Practice location
- 800 S Main St, Corona, CA 92882
- Phone
- (951) 737-4343
- Enumerated
- Mar 25, 2019
- Record last updated
- Jul 10, 2023
- Medicare enrollment
- Enrolled (PECOS I20230719004150); accepts Medicare assignment
- Medical or professional school
- University Of North Texas Hsc, College Of Osteopathic Med, 2019
- Entity
- Type 1 · individual
8 nearest emergency medicine physician records → All 7,751 in California → Look up another NPI →
Also registered at 800 S Main St
A shared address usually means a shared clinic or building; it does not show who employs whom.
- Charles Addo-Yobo, DOEmergency Medicine Physician1821625955
- James Ahn, M.D.Anesthesiology Physician1588641963
- Julie Ahn, PA-CPhysician Assistant1346802543
- Thomas Assali, DOInternal Medicine Physician1598225062
- Cynthia Bailey, P.A.-CPhysician Assistant1316053036
- David Bear, M.D.Emergency Medicine Physician1114033883
Verify Joaquin Castillo Marroquin in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersMedical Board of California
Search for license 202A20916Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
1% fewer Medicare Part D claims than the average emergency medicine physician in 2024
224 Medicare Part D claims for 161 beneficiaries, against an average of 226 among the 54,106 providers of this specialty who prescribed in Part D. 19 claims were for opioids.
Most prescribed
- Naproxen45 claims
- Cefpodoxime Proxetil31 claims
- Famotidine19 claims
- Oxycodone-Acetaminophen17 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.
Bills Medicare through one group practice
- Southern California Permanente Medical GroupRiverside, CA
Source: CMS Doctors and Clinicians National Downloadable File (the group practices a clinician bills Medicare through) (data.cms.gov).
Joaquin Castillo Marroquin among 7,751 emergency medicine physician records in California
Joaquin Castillo Marroquin, DO is one of 7,751 emergency 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 2019, is newer than 85% of them.
- NPI issued2019 · 85% of these records are older, 12% newer
- In a Medicare fileYes · 81% of these records are
- In the CMS Doctors and Clinicians fileYes · 59% of these records are
- Graduated2019 · median 2011 among the 4,560 with a school on file
- Record last updated2023 · 59% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 207P00000X and a California practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
Emergency Medicine Physician providers in California
There are 7,751 emergency medicine physician records in California.
All 7,751 in California → Every provider in Corona → Emergency Medicine Physician nationwide →
The 8 emergency medicine physician records with the nearest ZIP codes
- Charles Addo-Yobo, DOCorona, CA 928821821625955
- David Bear, M.D.Corona, CA 928821114033883
- Neil Bhutwala, DOCorona, CA 928821316500408
- James Boyd, M.D.Corona, CA 928821184730855
- Louis Chau, M.D.Corona, CA 928821225144918
- Nancy Chung, MDCorona, CA 928821275577447
- Tam Dang, M.D.Corona, CA 928821275824799
- Aakanksha Fenster, M.D.Corona, CA 928821659661163
Common questions
What is Joaquin Castillo Marroquin, DO's NPI number?
Joaquin Castillo Marroquin, DO's National Provider Identifier (NPI) is 1316407323, issued on Mar 25, 2019. An NPI identifies a provider in billing; it is not a license.
Where is Joaquin Castillo Marroquin, DO located?
The NPPES record lists a practice address at 800 S Main St, Corona, CA, 92882. Phone: (951) 737-4343. Providers update this record themselves, so call before visiting.
How can I verify Joaquin Castillo Marroquin, DO's license?
NPPES lists California license number 202A20916, 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 Joaquin Castillo Marroquin, DO prescribe under Medicare Part D?
In 2024, Joaquin Castillo Marroquin, DO had 224 Medicare Part D claims for 161 beneficiaries; the average among emergency medicine physician prescribers was 226. 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.