Marjolein Sieczkowski, LCSW
NPI 1457850984 · Clinical Social Worker · Flagstaff, AZ
Enrolled with Medicare as Practitioner - Clinical Social Worker · source: CMS PECOS Public Provider Enrollment (2026.04.01)
Marjolein Sieczkowski, LCSW is a Clinical Social Worker provider in Flagstaff, AZ (NPI 1457850984).
Provider details
- NPI number
- 1457850984
- Entity type
- Individual
- Primary specialty
- Clinical Social WorkerBehavioral Health & Social Service Providers
- Credential
- LCSW
- Sex
- Female
- Sole proprietor
- Yes
- License
- LCSW-16963 (AZ)
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
8 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
- 2018-02-10
- Last updated
- 2018-02-10
Frequently asked questions
- What is Marjolein Sieczkowski's NPI number?
- Marjolein Sieczkowski's National Provider Identifier (NPI) is 1457850984, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is Marjolein Sieczkowski's specialty?
- Marjolein Sieczkowski is listed in the NPPES registry with a primary specialty of Clinical Social Worker (Behavioral Health & Social Service Providers).
- Where is Marjolein Sieczkowski located?
- Marjolein Sieczkowski's practice location on file with NPPES is 125 E Elm Ave Ste 203, Flagstaff, AZ 86001-3261.
- What is Marjolein Sieczkowski's phone number?
- The practice phone number listed in the NPPES registry for Marjolein Sieczkowski is (480) 466-2428.
- Does Marjolein Sieczkowski accept Medicare?
- Marjolein Sieczkowski is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is Marjolein Sieczkowski's NPI active?
- Yes — Marjolein Sieczkowski's NPI (1457850984) is active in the NPPES registry as of the last update on 2018-02-10.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.