John Duff
NPI 1962732719 · Addiction (Substance Use Disorder) Counselor · Nevada City, CA
John Duff is a Addiction (Substance Use Disorder) Counselor provider in Nevada City, CA (NPI 1962732719).
Provider details
- NPI number
- 1962732719
- Entity type
- Individual
- Primary specialty
- Addiction (Substance Use Disorder) CounselorBehavioral Health & Social Service Providers
- Sex
- Male
- Sole proprietor
- No
- License
- 9852 (CA)
Specialties & taxonomies
Behavioral Health & Social Service Providers
Profile Score
A profile completeness & documented-activity index — NOT a quality, outcomes, or patient-satisfaction rating.
- Registry tenure38% of score
16 yrs in NPPES registry
- Profile completeness38% of score
100% of core fields populated
- Practice footprint23% of score
1 documented practice location
Signals a provider has no public data for (e.g. Medicare claims) are left out of the score entirely — never counted as zero — so providers without that data are not penalized. See the full formula and weights in our methodology.
Practice location
Mailing address
Registry dates
- Enumerated
- 2009-12-29
- Last updated
- 2009-12-29
Frequently asked questions
- What is John Duff's NPI number?
- John Duff's National Provider Identifier (NPI) is 1962732719, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is John Duff's specialty?
- John Duff is listed in the NPPES registry with a primary specialty of Addiction (Substance Use Disorder) Counselor (Behavioral Health & Social Service Providers).
- Where is John Duff located?
- John Duff's practice location on file with NPPES is 727 Zion St, Nevada City, CA 95959-2920.
- What is John Duff's phone number?
- The practice phone number listed in the NPPES registry for John Duff is (530) 265-2914.
- Is John Duff's NPI active?
- Yes — John Duff's NPI (1962732719) is active in the NPPES registry as of the last update on 2009-12-29.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.