NATHANIEL ERIC SIEV MD
NPI 1023515269
Anesthesiology in Tacoma, WA
About Nathaniel Eric Siev Md NPPES
Official registry information on file with the National Plan and Provider Enumeration System.
NATHANIEL ERIC SIEV MD (NPI 1023515269) is an individual anesthesiology provider in Tacoma, Washington, licensed in Washington (MD61218481) and active in the NPI registry since April 2018. He is enrolled in Medicare PECOS, is affiliated with St Joseph Medical Center, and maintains a secondary practice location in Seattle.
NPPES Registry Identity
Specialties & Licenses
Secondary Practice Location 1
Other Identifiers 1
Accepted Insurance
Medicare Participation & PECOS CMS
Medicare enrollment, assignment, billing reassignment, and ordering and referring status from CMS.
Medicare Enrollment Status
Enrolled in Medicare and accepts Medicare assignment
Nathaniel Eric Siev Md is registered in PECOS and agrees to accept the Medicare-approved amount as full payment. Medicare patients are not billed beyond the standard deductible and coinsurance.
Medicare Billing Reassignments
5Medicare enrollment records show Nathaniel Siev reassigns Medicare billing to 5 organizations. Each organization bills Medicare for the services this provider delivers there; the nearest is listed first.
Tacoma, WA 98402
- Reassigned Medicare billing, Washington enrollment
- 1,526 clinicians in this Medicare group
Seattle, WA 98104
- Reassigned Medicare billing, Washington enrollment
- 4,364 clinicians in this Medicare group
Seattle, WA 98104
- Reassigned Medicare billing, Washington enrollment
- Medicare enrollment name: Physicians Anesthesia Service PLLC
- 233 clinicians in this Medicare group
Seattle, WA 98101
- Reassigned Medicare billing, Washington enrollment
- 1,021 clinicians in this Medicare group
Everett, WA 98201
- Reassigned Medicare billing, Washington enrollment
- Medicare enrollment name: Providence Wa Anesthesia Services, PC
- 171 clinicians in this Medicare group
Source: CMS Revalidation Reassignment List, October 2026 release. Reassignment records can lag staffing changes; confirm a current affiliation with the organization.
Areas of Expertise CMS Part B claims
Services this provider delivered to Medicare fee-for-service patients, from the CMS Medicare utilization data. Higher counts generally reflect more experience with a service; care delivered outside Medicare is not included.
Hospital Affiliations CMS Care Compare
Hospitals where this provider delivers care, identified from recent Medicare claims and place-of-service records.
St Joseph Medical Center
Acute Care Hospitals · Tacoma, WAMedicare Quality Performance CMS QPP · MIPS
Performance in the CMS Quality Payment Program: the MIPS final score across four weighted categories, and the individual quality measures reported to Medicare.
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.
TACOMA, WA 98405
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 Nathaniel Siev's NPI number?
The NPI number for Nathaniel Siev is 1023515269. It was assigned to this individual provider in the NPPES registry on April 12, 2018.
Where is Nathaniel Siev located?
Nathaniel Siev practices at 1717 S J St, Tacoma, WA 98405. The listed phone number is (253) 426-4101.
What is Nathaniel Siev's specialty?
The primary specialty registered for this NPI is Anesthesiology with taxonomy code 207L00000X.
Is Nathaniel Siev enrolled in Medicare?
Yes. Nathaniel Siev is registered in the Medicare PECOS system and accepts Medicare assignment, which means accepting the Medicare-approved amount as payment in full for covered services.
Which organizations bill Medicare for Nathaniel Siev's services?
According to the CMS Revalidation Reassignment List (October 2026 release), Nathaniel Siev reassigns Medicare benefits to 5 organizations: Franciscan Medical Group (Tacoma, WA), The Association Of University Physicians (Seattle, WA), Proliance Surgeons, Inc., P.S. (Seattle, WA), Virginia Mason Medical Center (Seattle, WA) and Providence Wa Anesthesia Services, P.C. (Everett, WA). Each 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 Nathaniel Siev's services. Reassignment records can lag staffing changes; confirm current arrangements with the organization.
What insurance does Nathaniel Siev accept?
Health plans from Ambetter Health and Premera Blue Cross Blue Shield of Alaska list Nathaniel Siev as in-network in at least one marketplace plan. Coverage varies by plan and year; verify with the insurer or the provider before a visit.
Is Nathaniel Siev affiliated with any hospitals?
According to CMS data, Nathaniel Siev is affiliated with St Joseph Medical Center.
When was this NPI record last updated?
The NPPES record for Nathaniel Siev was last updated on December 30, 2025. NPI Profile syncs weekly with the NPPES registry data releases published by CMS. This NPI record was last updated 10 months 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.
# Nathaniel Eric Siev, MD · NPI 1023515269
Anesthesiology physician in Tacoma, Washington. Individual provider, active in the CMS NPPES registry since April 12, 2018.
## Identity
- **NPI:** 1023515269 (Entity type: Individual)
- **Enumerated:** April 12, 2018
- **Primary specialty:** Anesthesiology · taxonomy 207L00000X
- **State license:** MD61218481 (Washington)
- **Sole proprietor:** No
## Practice location
- **Address:** 1717 S J ST, Tacoma, WA 98405-4933
- **Phone:** (253) 426-4101
## Medicare
- **Medicare:** Enrolled (PECOS); accepts Medicare assignment
- **Ordering & referring:** eligible for Part B labs & imaging, durable medical equipment, home health, power mobility devices
- **Bills Medicare through:** 5 organizations under Medicare reassignment (form CMS-855R): Franciscan Medical Group (NPI 1831358282, Tacoma, WA); The Association Of University Physicians (NPI 1023041159, Seattle, WA); Proliance Surgeons, Inc., P.S. (NPI 1811936990, Seattle, WA); Virginia Mason Medical Center (NPI 1003970989, Seattle, WA); Providence Wa Anesthesia Services, P.C. (NPI 1669615894, Everett, WA) · CMS Revalidation Reassignment List, October 2026 release
- **Medical school:** Other, class of 2018
## Record status
- **NPPES last updated:** December 30, 2025
- **Other identifiers:** Medicaid 2205683 (WA)
---
Source: [NPI Profile](https://npiprofile.com/npi/1023515269) · Data from the CMS NPPES public registry.