JUSTIN T CASTELLOW MD
NPI 1639565344
Pediatrics - Neonatal-Perinatal Medicine in Marshfield, WI
About Justin T Castellow Md NPPES
Official registry information on file with the National Plan and Provider Enumeration System.
JUSTIN T CASTELLOW MD (NPI 1639565344) is an individual neonatal-perinatal medicine provider in Marshfield, Wisconsin, licensed in Wisconsin (15512) and active in the NPI registry since April 2015. He is enrolled in Medicare PECOS and maintains a secondary practice location in Millcreek.
NPPES Registry Identity
Specialties & Licenses 2
Secondary Practice Location 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 (PECOS)
Justin T Castellow Md is registered in the CMS Provider Enrollment, Chain and Ownership System (PECOS).
Medicare Billing Reassignments
6Medicare enrollment records show Justin Castellow reassigns Medicare billing to 6 organizations. Each organization bills Medicare for the services this provider delivers there; the nearest is listed first.
Marshfield, WI 54449
- Reassigned Medicare billing, Wisconsin enrollment
- 2,540 clinicians in this Medicare group
Marshfield, WI 54449
- Reassigned Medicare billing, Wisconsin enrollment
- Also billed through NPI 1952890873 (Wisconsin)
- 2,476 clinicians in this Medicare group
Neillsville, WI 54456
- Reassigned Medicare billing, Wisconsin enrollment
- Also billed through NPI 1346239373 (Wisconsin)
- 1,283 clinicians in this Medicare group
Chetek, WI 54728
- Reassigned Medicare billing, Wisconsin enrollment
- 1,616 clinicians in this Medicare group
Park Falls, WI 54552
- Reassigned Medicare billing, Wisconsin enrollment
- Also billed through NPI 1700963048 (Wisconsin)
- 1,351 clinicians in this Medicare group
Waupun, WI 53963
- Reassigned Medicare billing, Wisconsin enrollment
- 1,447 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.
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.
MARSHFIELD, WI 54449
MARSHFIELD, WI 54449
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 Justin Castellow's NPI number?
The NPI number for Justin Castellow is 1639565344. It was assigned to this individual provider in the NPPES registry on April 9, 2015.
Where is Justin Castellow located?
Justin Castellow practices at 1000 N Oak Ave, Marshfield, WI 54449. The listed phone number is (715) 387-5511.
What is Justin Castellow's specialty?
The primary specialty registered for this NPI is Pediatrics, specializing in Neonatal-Perinatal Medicine, with taxonomy code 2080N0001X.
Is Justin Castellow enrolled in Medicare?
Yes. Justin Castellow is registered in the Medicare PECOS enrollment system.
Which organizations bill Medicare for Justin Castellow's services?
According to the CMS Revalidation Reassignment List (October 2026 release), Justin Castellow reassigns Medicare benefits to 6 organizations: Marshfield Clinic Inc (Marshfield, WI), Mchs Hospitals Inc (Marshfield, WI), Memorial Hospital, Inc (Neillsville, WI), Lakeview Medical Center Inc Of Rice Lake (Chetek, WI), Flambeau Hospital Inc (Park Falls, WI) and 1 more organization, listed in the Medicare section above. 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 Justin Castellow's services. Reassignment records can lag staffing changes; confirm current arrangements with the organization.
What insurance does Justin Castellow accept?
Health plans from HealthPartners and Sanford Health Plan list Justin Castellow 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.
When was this NPI record last updated?
The NPPES record for Justin Castellow was last updated on August 27, 2026. NPI Profile syncs weekly with the NPPES registry data releases published by CMS. This NPI record was last updated 58 days 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.
# Justin T Castellow, MD · NPI 1639565344
Neonatal-Perinatal Medicine physician in Marshfield, Wisconsin. Individual provider, active in the CMS NPPES registry since April 9, 2015.
## Identity
- **NPI:** 1639565344 (Entity type: Individual)
- **Enumerated:** April 9, 2015
- **Primary specialty:** Pediatrics - Neonatal-Perinatal Medicine · taxonomy 2080N0001X
- **State license:** 15512 (Wisconsin)
- **Sole proprietor:** No
## Practice location
- **Address:** 1000 N OAK AVE, Marshfield, WI 54449-5703
- **Phone:** (715) 387-5511
## Medicare
- **Medicare:** Enrolled in Medicare (PECOS)
- **Ordering & referring:** eligible for Part B labs & imaging, durable medical equipment, home health, power mobility devices
- **Bills Medicare through:** 6 organizations under Medicare reassignment (form CMS-855R): Marshfield Clinic Inc (NPI 1952347981, Marshfield, WI); Mchs Hospitals Inc (NPI 1093221434, Marshfield, WI); Memorial Hospital, Inc (NPI 1679746747, Neillsville, WI); Lakeview Medical Center Inc Of Rice Lake (NPI 1659008605, Chetek, WI); Flambeau Hospital Inc (NPI 1194317966, Park Falls, WI); and 1 more · CMS Revalidation Reassignment List, October 2026 release
## Record status
- **NPPES last updated:** August 27, 2026
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Source: [NPI Profile](https://npiprofile.com/npi/1639565344) · Data from the CMS NPPES public registry.