ROBERT C DAY M.D.
NPI 1841618634
Obstetrics & Gynecology - Maternal & Fetal Medicine in Irvine, CA

Q: What is Robert Day's NPI number?

The NPI number for Robert Day is 1841618634. It was assigned to this individual provider in the NPPES registry on March 31, 2014.

Q: What is Robert Day's specialty?

The primary specialty registered for this NPI is Obstetrics & Gynecology, specializing in Maternal & Fetal Medicine, with taxonomy code 207VM0101X.

Q: When was this NPI record last updated?

The NPPES record for Robert Day was last updated on June 17, 2025. NPI Profile syncs weekly with the NPPES registry data releases published by CMS. This NPI record was last updated 16 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.

Active since March 31, 2014PECOS EnrolledAccepts Medicare Assignment

16305 SAND CANYON AVE STE 225, IRVINE, CA 92618(949) 763-7451 Get Directions Write a Review

NPPES record last updated: June 17, 2025. Verified against the NPPES registry weekly; last sync: October 25, 2026.

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About Robert C Day M.d. NPPES

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

ROBERT C DAY M.D. (NPI 1841618634) is an individual maternal & fetal medicine provider in Irvine, California, licensed in California (A139689) and active in the NPI registry since March 2014. He is enrolled in Medicare PECOS, maintains a secondary practice location in Santa Clara, and is a graduate of University Of Massachusetts Medical School (2014).

NPPES Registry Identity

NPI1841618634

Entity TypeIndividualMale

Primary Taxonomy207VM0101X

Provider Legal NameROBERT C DAYCredential: M.D.

Location Address16305 SAND CANYON AVE STE 225Irvine, CA 92618-3795

Mailing Address395 Central StMilford, MA 01757-3401

Phone(949) 763-7451

Sole ProprietorNo

Medical School CMSUniversity Of Massachusetts Medical SchoolGraduated 2014

Enumeration DateMarch 31, 2014

Last NPPES UpdateJune 17, 2025

NPPES CertifiedJune 17, 2025

✔ NPI 1841618634 is a valid, active identifier and passes the ISO check-digit test.

Specialties & Licenses 2

★ Primary SpecialtyObstetrics & Gynecology · Maternal & Fetal MedicineAllopathic & Osteopathic Physicians

Taxonomy Code207VM0101X

License✔ Licensed in CA · A139689

Definition

An obstetrician/gynecologist who cares for, or provides consultation on, patients with complications of pregnancy. This specialist has advanced knowledge of the obstetrical, medical and surgical complications of pregnancy and their effect on both the mother and the fetus. The specialist also possesses expertise in the most current diagnostic and treatment modalities used in the care of patients with complicated pregnancies.

Also ListedObstetrics & GynecologyTaxonomy 207V00000X · License A139689 (CA)

16305 SAND CANYON AVE STE 225, Irvine, CA 92618

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Secondary Practice Location 1

Location 1700 Lawrence ExpySanta Clara, CA 95051-5173 · Phone (408) 851-1000

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

Robert C Day 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 ID6204129315

PECOS Enrollment IDI20180425001142

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

Medicare enrollment records show Robert Day reassigns Medicare billing to 3 organizations. Each organization bills Medicare for the services this provider delivers there; the nearest is listed first.

University Of California Irvine

8.2 mi

Federally Qualified Health Center (FQHC)

800 N MAIN ST
Santa Ana, CA 92701

Reassigned Medicare billing, California enrollment
255 clinicians in this Medicare group

NPI 1851325906 (714) 456-6785

Hoag Clinic

9.2 mi

Primary Care

510 SUPERIOR AVE
Newport Beach, CA 92663

Reassigned Medicare billing, California enrollment
529 clinicians in this Medicare group

NPI 1942799523 (949) 791-3001

Regents Of The University Of California

11 mi

Obstetrics & Gynecology

101 CITY DRIVE SOUTH, BLDG 56 SUITE 800
Orange, CA 92868

Reassigned Medicare billing, California enrollment
149 clinicians in this Medicare group

NPI 1356304034 (714) 456-6431

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

Physician Visit Costs CMS claims · ZIP area

Typical Medicare office-visit costs in the 92618 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

$142.39 typical visit price

range $62.96 – $187.60

Typical copayment $35.59 (range $15.74 – $46.90)

Most-billed visit code 99204

Established Patient

$77.96 typical visit price

range $20.84 – $153.61

Typical copayment $19.49 (range $5.21 – $38.40)

Most-billed visit code 99213

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

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

MICHAEL L HAYDON MD

Obstetrics & Gynecology (Maternal & Fetal Medicine)

16305 SAND CANYON AVE STE 225
IRVINE, CA 92618

Orange County (714) 488-6690

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 Robert Day's NPI number?

The NPI number for Robert Day is 1841618634. It was assigned to this individual provider in the NPPES registry on March 31, 2014.

Where is Robert Day located?

Robert Day practices at 16305 Sand Canyon Ave Ste 225, Irvine, CA 92618. The listed phone number is (949) 763-7451.

What is Robert Day's specialty?

The primary specialty registered for this NPI is Obstetrics & Gynecology, specializing in Maternal & Fetal Medicine, with taxonomy code 207VM0101X.

Is Robert Day enrolled in Medicare?

Yes. Robert Day 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 Robert Day's services?

According to the CMS Revalidation Reassignment List (October 2026 release), Robert Day reassigns Medicare benefits to 3 organizations: University Of California Irvine (Santa Ana, CA), Hoag Clinic (Newport Beach, CA) and Regents Of The University Of California (Orange, CA). 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 Robert Day'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 Robert Day was last updated on June 17, 2025. NPI Profile syncs weekly with the NPPES registry data releases published by CMS. This NPI record was last updated 16 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.