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SIOBHAN MARK MS CCC-SLP
NPI 1487141974
Speech-Language Pathologist in Walnut Creek, CA

Active since April 19, 2018
320 LENNON LN, WALNUT CREEK, CA 94598(925) 906-2000 Get Directions Write a Review

NPPES record last updated: February 11, 2022. Verified against the NPPES registry weekly; last sync: November 01, 2026.

Record update history: Feb 11, 2022, Apr 19, 2018 (2 updates tracked since 2018).

About Siobhan Mark Ms Ccc-slp NPPES

Official registry information on file with the National Plan and Provider Enumeration System.

SIOBHAN MARK MS CCC-SLP (NPI 1487141974) is an individual speech-language pathologist provider in Walnut Creek, California, licensed in California (12149) and active in the NPI registry since April 2018. She maintains a secondary practice location in Walnut Creek.

NPPES Registry Identity

NPI1487141974
Entity TypeIndividualFemale
Primary Taxonomy235Z00000X
Provider Legal NameSIOBHAN MARKCredential: MS CCC-SLP
Location Address320 LENNON LNWalnut Creek, CA 94598-2419
Mailing Address1242 Spruce StBerkeley, CA 94709-1433 · (510) 323-6946
Phone(925) 906-2000
Sole ProprietorYes
Enumeration DateApril 19, 2018
Last NPPES UpdateFebruary 11, 20222 updates tracked since enumeration
✔ NPI 1487141974 is a valid, active identifier and passes the ISO check-digit test.

Specialties & Licenses

★ Primary SpecialtySpeech-Language PathologistSpeech, Language and Hearing Service Providers
Taxonomy Code235Z00000X
License✔ Licensed in CA · 12149
Definition
The speech-language pathologist is the professional who engages in clinical services, prevention, advocacy, education, administration, and research in the areas of communication and swallowing across the life span from infancy through geriatrics. Speech-language pathologists address typical and atypical impairments and disorders related to communication and swallowing in the areas of speech sound production, resonance, voice, fluency, language (comprehension and expression), cognition, and feeding and swallowing.
320 LENNON LN, Walnut Creek, CA 94598
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Secondary Practice Location 1

Location 11425 S Main StWalnut Creek, CA 94596-5318 · Phone (925) 295-4000

Group Practice 1

Group TaxonomyThis provdier is a business group of one or more individual practitioners, all of who practice with the same area of specialization.193400000X SINGLE SPECIALTY GROUP

Medicare Participation & PECOS CMS

Medicare enrollment, assignment, billing reassignment, and ordering and referring status from CMS.

Medicare Enrollment Status

✔

Enrolled in Medicare (PECOS)

Siobhan Mark Ms Ccc-slp is registered in the CMS Provider Enrollment, Chain and Ownership System (PECOS).

Medicare Billing Reassignment

Medicare enrollment records show Siobhan Mark reassigns Medicare billing to 1 organization. The organization bills Medicare for the services this provider delivers there.

Permanente Medical Group Inc
18 mi
Internal Medicine
901 NEVIN
Richmond, CA 94801
  • Reassigned Medicare billing, California enrollment
  • 20,078 clinicians in this Medicare group
NPI 1235226531 (510) 307-1555

Source: CMS Revalidation Reassignment List, October 2026 release. Reassignment records can lag staffing changes; confirm a current affiliation with the organization.

Other Providers at the Same Location NPPES 20

Providers registered at the same practice address, or within the immediate area, according to the NPPES registry.

LINDA MARIE HECKENLIVELY M.S., CCC-SLP
Speech-Language Pathologist
320 LENNON LN
WALNUT CREEK, CA 94598
Contra Costa County (925) 906-2268
DR. NEGAR DOLATSHAHI PIROOZ OD
Optometrist
320 LENNON LN
WALNUT CREEK, CA 94598
Contra Costa County (925) 906-2156
KARIN HESS BRIGHT PT
Physical Therapist (Hand)
320 LENNON LN
WALNUT CREEK, CA 94598
Contra Costa County (925) 906-2055
STEPHANIE M. PO MD
Ophthalmology
320 LENNON LN
WALNUT CREEK, CA 94598
Contra Costa County (925) 906-2000
MR. DAVID NATHANSON
Internal Medicine
320 LENNON LN
WALNUT CREEK, CA 94598
Contra Costa County (925) 906-2000
DR. KENNETH MUN LEE O.D.
Optometrist
320 LENNON LN
WALNUT CREEK, CA 94598
Contra Costa County (925) 906-2171
JUDY KWAK
Pharmacist
320 LENNON LN
WALNUT CREEK, CA 94598
Contra Costa County (925) 906-2503
DR. TIMMOTHY O MERRIGAN M.D.
Family Medicine
320 LENNON LN
WALNUT CREEK, CA 94598
Contra Costa County (924) 906-2326

Frequently Asked Questions NPPES & CMS

Common questions about this NPI record, answered from the official NPPES registry and CMS datasets shown on this page.

What is Siobhan Mark's NPI number?

The NPI number for Siobhan Mark is 1487141974. It was assigned to this individual provider in the NPPES registry on April 19, 2018.

Where is Siobhan Mark located?

Siobhan Mark practices at 320 Lennon Ln, Walnut Creek, CA 94598. The listed phone number is (925) 906-2000.

What is Siobhan Mark's specialty?

The primary specialty registered for this NPI is Speech-Language Pathologist with taxonomy code 235Z00000X.

Is Siobhan Mark enrolled in Medicare?

Yes. Siobhan Mark is registered in the Medicare PECOS enrollment system.

Which organization bills Medicare for Siobhan Mark's services?

According to the CMS Revalidation Reassignment List (October 2026 release), Siobhan Mark reassigns Medicare benefits to Permanente Medical Group Inc (Richmond, CA). The reassignment is filed with Medicare on form CMS-855R, signed by both the clinician and the organization, and lets the organization bill Medicare and receive payment for Siobhan Mark's services. Reassignment records can lag staffing changes; confirm current arrangements with the organization.

When was this NPI record last updated?

The NPPES record for Siobhan Mark was last updated on February 11, 2022. NPI Profile syncs weekly with the NPPES registry data releases published by CMS. This NPI record was last updated 4 years ago. If this record has changed at CMS more recently, you can request an on-demand re-check against the live CMS registry, directly from this page.