Mark Hernandez
Mark Hernandez is an Addiction (Substance Use Disorder) Counselor in Fairfield, CA, registered under NPI 1003536384. NPPES records them as a sole proprietor, meaning the practice is not incorporated as a separate legal entity.
Getting there
Here is what surrounds this office in Fairfield, based on OpenStreetMap data collected Oct 4, 2026. Parking is available about 0.28 mi away. There is EV charging 0.26 mi from the office — useful if you are driving in from out of town. The nearest transit stop is 0.23 mi away, served by Fairfield Civic Center. If you arrive early, there is a coffee shop 0.30 mi away.
Getting here and what is nearby
Gas station Chevron 599 ft ~3 min
Transit W Texas St & Pennsylvania Ave 949 ft ~4 min
Parking 0.21 mi ~5 min
Restaurant Joe’s Buffet 0.22 mi ~5 min
834 Texas Street, Fairfield 94533
Transit Pennsyvlania Ave and Kentucky St 0.23 mi ~5 min
Transit Fairfield Civic Center 0.23 mi ~5 min
Hotel Econo Lodge 0.25 mi ~5 min
Parking 0.25 mi ~6 min
EV charging 0.26 mi ~6 min
Gas station 76 0.28 mi ~6 min
Parking 0.28 mi ~6 min
Coffee Dutch Bros. Coffee 0.30 mi ~7 min
1420 West Texas Street, Fairfield 94533
Mo 05:30-22:00; Tu 05:30-17:00; We-Th 05:30-22:00; Fr-Sa 05:30-23:00; Su 05:30-22:00
Convenience Circle K 0.30 mi ~6 min
Restaurant Three Restaurant 0.30 mi ~7 min
Restaurant Subway 0.44 mi ~9 min
1513 West Texas Street, Fairfield 94533
Mo-Sa 08:00-21:30; Su 09:00-21:00
Distances are straight‑line estimates — walking routes may be longer. Hours and phone numbers can change; call ahead to confirm.
Credentials and Medicare
NPPES does not list a state licence number for this record. That is not unusual — organizations and some provider types are not required to file one. Verify current licensure with the relevant state board before care.
This NPI does not appear in the PECOS Medicare enrolment file. Providers who do not bill Medicare — or who bill only through a group's enrolment — will not appear here. It is not a sign of any problem with the registration.
What Addiction (Substance Use Disorder) covers
Definition to come... NUCC Health Care Provider Taxonomy, code 101YA0400X
The taxonomy records how the provider classifies their own practice. It does not confirm which conditions they currently treat, whether they are accepting new patients, or which insurance they take — call the office for that.
Full NPPES record
An NPI-1 identifies a single person. It stays with the clinician for life, even if they move practice or change state, which is why the address on file can lag behind where they actually work today.
| NPI | 1003536384 valid check digit |
|---|---|
| Entity type | Individual (NPI-1) |
| Enumeration date | Aug 29, 2022 |
| Last updated | Sep 11, 2025 |
| Status | Active |
| Sole proprietor | Yes |
| Gender | Male |
| Practice address |
1143 MISSOURI ST Fairfield, CA 94533 (707) 435-9911 |
Number check
How the check works, step by step
Every NPI carries a Luhn check digit — the same scheme used on credit cards. CMS prefixes the number with 80840 before computing it, which marks it as a US health identifier.
| Digit | 8 | 0 | 8 | 4 | 0 | 1 | 0 | 0 | 3 | 5 | 3 | 6 | 3 | 8 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Doubled? | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 |
| Value | 8 | 0 | 8 | 8 | 0 | 2 | 0 | 0 | 3 | 1 | 3 | 3 | 3 | 7 |
Sum = 46 · next multiple of 10 = 50 · check digit = 4 · actual last digit = 4
A valid check digit only means the number is well-formed. It does not mean the provider is licensed, active, or in good standing — those are separate questions answered by the sections above.