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KATHERINE MADISON MACMILLAN M.D.
NPI 1780117416
Internal Medicine - Gastroenterology in Simpsonville, SC

Active since April 10, 2017PECOS EnrolledAccepts Medicare Assignment
741 SE MAIN ST, SIMPSONVILLE, SC 29681(864) 522-8420(864) 522-8425 Get Directions Write a Review

NPPES record last updated: February 23, 2026. Verified against the NPPES registry weekly; last sync: October 18, 2026.

Record update history: Apr 26, 2024, Jul 21, 2022, Mar 17, 2018 and 2 more (5 updates tracked since 2017).

About Katherine Madison Macmillan M.d. NPPES

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

KATHERINE MADISON MACMILLAN M.D. (NPI 1780117416) is an individual gastroenterology provider in Simpsonville, South Carolina, licensed in South Carolina (85580) and active in the NPI registry since April 2017. She is enrolled in Medicare PECOS, is affiliated with Prisma Health Baptist Easley Hospital, and maintains 2 additional practice locations.

NPPES Registry Identity

NPI1780117416
Entity TypeIndividualFemale
Primary Taxonomy207RG0100X
Provider Legal NameKATHERINE MADISON MACMILLANCredential: M.D.
Location Address741 SE MAIN STSimpsonville, SC 29681-3237
Mailing Address300 E Mcbee Ave Ste 300Greenville, SC 29601-2899 · (864) 522-8603
Phone(864) 522-8420
Fax(864) 522-8425
Sole ProprietorNo
Medical School CMSOtherGraduated 2017
Enumeration DateApril 10, 2017
Last NPPES UpdateFebruary 23, 20265 updates tracked since enumeration
NPPES CertifiedFebruary 23, 2026
✔ NPI 1780117416 is a valid, active identifier and passes the ISO check-digit test.

Specialties & Licenses 2

★ Primary SpecialtyInternal Medicine · GastroenterologyAllopathic & Osteopathic Physicians
Taxonomy Code207RG0100X
Licenses✔ Licensed in SC · 85580✔ Licensed in AZ · 72379
Definition
An internist who specializes in diagnosis and treatment of diseases of the digestive organs including the stomach, bowels, liver and gallbladder. This specialist treats conditions such as abdominal pain, ulcers, diarrhea, cancer and jaundice and performs complex diagnostic and therapeutic procedures using endoscopes to visualize internal organs.
Also ListedInternal MedicineTaxonomy 207R00000X · License 85580 (SC), 009641 (GA)
741 SE MAIN ST, Simpsonville, SC 29681
Open in Google Maps ↗

Secondary Practice Locations 2

Location 1727 SE Main St Ste 340Simpsonville, SC 29681-3249 · Phone (864) 455-2888 · Fax (864) 455-2885
Location 213400 E Shea BlvdScottsdale, AZ 85259-5499 · Phone (480) 301-8000

Accepted Insurance

The full list of accepted plans is on the Insurance tab. Issuers include Ambetter from Absolute Total Care, Ambetter of North Carolina, BlueCross BlueShield of South Carolina and more.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

Katherine Madison Macmillan M.d. 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.

PECOS PAC ID8426312141
PECOS Enrollment IDI20250616002806
Eligible to Order & Refer✔ Part B Labs & Imaging✔ Durable Medical Equipment✔ Home Health Agency✔ Power Mobility DevicesPer the CMS Ordering and Referring file. Eligibility means Medicare pays claims that this provider orders or refers for these categories.

Medicare Billing Reassignments

2

Medicare enrollment records show Katherine Macmillan reassigns Medicare billing to 2 organizations. Each organization bills Medicare for the services this provider delivers there; the nearest is listed first.

Prisma Health University Medical Group
8.9 mi
Internal Medicine
1025 VERDAE BLVD, SUITE A
Greenville, SC 29607
  • Reassigned Medicare billing, South Carolina enrollment
  • 3,281 clinicians in this Medicare group
NPI 1083787006 (864) 242-4683
Mayo Clinic Arizona
1,689 mi
Multi-Specialty
13400 E SHEA BLVD
Scottsdale, AZ 85259
  • Reassigned Medicare billing, Arizona enrollment
  • 1,792 clinicians in this Medicare group
NPI 1558332494 (480) 301-8000

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

Hospital Affiliations CMS Care Compare 5

Hospitals where this provider delivers care, identified from recent Medicare claims and place-of-service records.

Prisma Health Baptist Easley Hospital

Acute Care Hospitals · Easley, SC
3/5 CMS rating
OwnershipVoluntary non-profit - Private
CMS Certification Number420015
Location200 Fleetwood DriveEasley, SC 29640 · Pickens County
Emergency services

Prisma Health Hillcrest Hospital

Acute Care Hospitals · Simpsonville, SC
3/5 CMS rating
OwnershipVoluntary non-profit - Private
CMS Certification Number420037
Location741 South East Main StreetSimpsonville, SC 29681 · Greenville County
Emergency services

Prisma Health Laurens County Hospital

Acute Care Hospitals · Clinton, SC
3/5 CMS rating
OwnershipVoluntary non-profit - Private
CMS Certification Number420038
Location22725 Highway 76 EastClinton, SC 29325 · Laurens County
Emergency services Birthing friendly

Prisma Health Greenville Memorial Hospital

Acute Care Hospitals · Greenville, SC
3/5 CMS rating
OwnershipVoluntary non-profit - Private
CMS Certification Number420078
Location701 Grove RoadGreenville, SC 29605 · Greenville County
Birthing friendly

Prisma Health Patewood Hospital

Acute Care Hospitals · Greenville, SC
5/5 CMS rating
OwnershipVoluntary non-profit - Private
CMS Certification Number420102
Location175 Patewood DriveGreenville, SC 29615 · Greenville County
Birthing friendly

Physician Visit Costs CMS claims · ZIP area

Typical Medicare office-visit costs in the 29681 ZIP code area, from fee-for-service claims. These are area statistics, not this provider’s prices; actual charges vary by service and coverage.

New Patient
$124.04 typical visit price
range $53.57 – $163.84
Typical copayment $31.01 (range $13.39 – $40.96)
Most-billed visit code 99204
Established Patient
$95.12 typical visit price
range $16.96 – $133.52
Typical copayment $23.78 (range $4.24 – $33.38)
Most-billed visit code 99214
Amounts reflect what Medicare beneficiaries in this ZIP area are typically charged for office visits. Patients with other coverage should check their individual plans.

Other Providers at the Same Location NPPES 2

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

JESSICA BOSEMAN NP
Nurse Practitioner (Family)
741 SE MAIN ST
SIMPSONVILLE, SC 29681
Greenville County (864) 522-8420
PRISMA HEALTH-UPSTATE
Clinic/Center (Sleep Disorder Diagnostic)
741 SE MAIN ST
SIMPSONVILLE, SC 29681
Greenville County (864) 455-7743

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 Katherine Macmillan's NPI number?

The NPI number for Katherine Macmillan is 1780117416. It was assigned to this individual provider in the NPPES registry on April 10, 2017.

Where is Katherine Macmillan located?

Katherine Macmillan practices at 741 SE Main St, Simpsonville, SC 29681. The listed phone number is (864) 522-8420.

What is Katherine Macmillan's specialty?

The primary specialty registered for this NPI is Internal Medicine, specializing in Gastroenterology, with taxonomy code 207RG0100X.

Is Katherine Macmillan enrolled in Medicare?

Yes. Katherine Macmillan 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 Katherine Macmillan's services?

According to the CMS Revalidation Reassignment List (October 2026 release), Katherine Macmillan reassigns Medicare benefits to 2 organizations: Prisma Health University Medical Group (Greenville, SC) and Mayo Clinic Arizona (Scottsdale, AZ). 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 Katherine Macmillan's services. Reassignment records can lag staffing changes; confirm current arrangements with the organization.

What insurance does Katherine Macmillan accept?

Health plans from Ambetter from Absolute Total Care, Ambetter of North Carolina, BlueCross BlueShield of South Carolina and InStil Health list Katherine Macmillan 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 Katherine Macmillan affiliated with any hospitals?

According to CMS data, Katherine Macmillan is affiliated with Prisma Health Baptist Easley Hospital, Prisma Health Hillcrest Hospital, Prisma Health Laurens County Hospital, Prisma Health Greenville Memorial Hospital and Prisma Health Patewood Hospital.

When was this NPI record last updated?

The NPPES record for Katherine Macmillan was last updated on February 23, 2026. NPI Profile syncs weekly with the NPPES registry data releases published by CMS. This NPI record was last updated 7 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.