Active NPI 1851688873 Individual Practitioner Female Practitioner

Marissa Williams , PA-C

Physician Assistant • Zephyrhills, FL

Professional Overview & Biography Verified Profile Summary

Marissa Williams, PA-C is a certified Physician Assistant practicing in Zephyrhills, FL. With approximately 15 years of clinical experience since completing medical education in 2011, Marissa Williams delivers high-quality medical care to the local community at 7213 GREEN SLOPE DR.

Marissa Williams maintains professional affiliations with Legacy Healthcare Services Inc, Zephyrhills Family Practice And Geriatric Care Llc and does not directly accept Medicare assignment.

Frequently performed procedures and clinical services include established patient outpatient office visit, insertion of needle into vein for collection of blood sample, annual wellness visit, includes a personalized prevention plan of service (pps), subsequent visit. Full Medicare procedure pricing transparency rates and service volume details are listed on this profile.

Practice Location & Contact Primary Location

Practice Address

7213 Green Slope Dr

Zephyrhills, FL 335411306

Telephone 8133554914

Fax 8555475415

Associated Practice Facility / Clinic

🏢 Zephyrhills Family Practice And Geriatric Care, Llc Facility NPI 1154825677

Medicare Profile & Education

Medical School

Other

Graduation Year

2011

Medicare Assignment

Not Specified

Telehealth Flag

In-Person Only

Specialty Benchmarks & Practice Insights

Comparative analytics for Physician Assistant in Zephyrhills, FL

Established Specialist (10-20 Yrs)

Practitioner Clinical Experience

15 Yrs +4.9 yrs vs City Avg

City Avg: 10.1 Yrs

State Avg: 11.1 Yrs

Regional Practice Density

32 Specialists

Practicing in Zephyrhills, FL (10376 Statewide)

Telehealth Adoption Rate

12.5% Regional Adoption

In-Person Office Visits Only

Medicare Pricing Discount

59.3% Avg Savings

Under CMS Medicare Fee Schedule vs Standard Submitted Charges

Clinical Seniority & Experience Comparison

Dr. Williams (15 Years) 15 Yrs

Zephyrhills Specialty Average (10.1 Years) 10.1 Yrs

Performed Procedures & Service Volume

Top Medicare Part B procedures performed by this practitioner

CMS Official Data (2024)

Reporting Year:

HCPCS Code & Description	Services	Patients	Submitted Charge	Medicare Allowed
99214 Established patient office or other outpatient visit with moderate level of decision making, if using time, 30 minutes or more	17	17	$260.00	$105.93

HCPCS Code & Description	Services	Patients	Submitted Charge	Medicare Allowed
99214 Established patient office or other outpatient visit with moderate level of decision making, if using time, 30 minutes or more	13	13	$163.56	$108.77

HCPCS Code & Description	Services	Patients	Submitted Charge	Medicare Allowed
99214 Established patient office or other outpatient visit with moderate level of decision making, if using time, 30 minutes or more	208	116	$163.56	$110.25
36415 Insertion of needle into vein for collection of blood sample	109	76	$28.00	$2.98
99213 Established patient office or other outpatient visit, typically 15 minutes	28	25	$112.85	$77.62
G0439 Annual wellness visit, includes a personalized prevention plan of service (pps), subsequent visit	21	21	$180.71	$112.06
81002 Urinalysis, manual test	14	12	$10.00	$3.48

HCPCS Code & Description	Services	Patients	Submitted Charge	Medicare Allowed
99214 Established patient office or other outpatient visit with moderate level of decision making, if using time, 30 minutes or more	165	104	$163.56	$92.04
36415 Insertion of needle into vein for collection of blood sample	86	71	$27.71	$2.96
99213 Established patient office or other outpatient visit, typically 15 minutes	53	41	$107.17	$62.87
81002 Urinalysis, manual test	15	13	$10.00	$3.42
G0439 Annual wellness visit, includes a personalized prevention plan of service (pps), subsequent visit	14	14	$176.00	$98.22

HCPCS Code & Description	Services	Patients	Submitted Charge	Medicare Allowed
99214 Established patient office or other outpatient visit with moderate level of decision making, if using time, 30 minutes or more	151	108	$297.00	$90.52
99213 Established patient office or other outpatient visit, typically 15 minutes	48	37	$202.00	$61.67
96372 Injection beneath the skin or into muscle for therapy, diagnosis, or prevention	25	15	$67.00	$17.06

HCPCS Code & Description	Services	Patients	Submitted Charge	Medicare Allowed
99214 Established patient office or other outpatient visit with moderate level of decision making, if using time, 30 minutes or more	551	175	$297.00	$89.42
J1100 Injection, dexamethasone sodium phosphate, 1 mg	392	34	$15.00	$0.11
99213 Established patient office or other outpatient visit, typically 15 minutes	172	106	$202.00	$61.35
J0696 Injection, ceftriaxone sodium, per 250 mg	125	26	$64.00	$0.66
96372 Injection beneath the skin or into muscle for therapy, diagnosis, or prevention	98	48	$67.00	$21.06
G0438 Annual wellness visit; includes a personalized prevention plan of service (pps), initial visit	45	45	$476.00	$143.24
G0008 Administration of influenza virus vaccine	44	41	$13.00	$12.45
81002 Urinalysis, manual test	38	30	$20.00	$3.43
J2010 Injection, lincomycin hcl, up to 300 mg	37	17	$29.00	$12.15
90662 Influenza vaccine split virus, preservative free	35	35	$89.00	$46.68
82962 Blood glucose (sugar) test performed by hand-held instrument	20	13	$11.00	$3.15
G0439 Annual wellness visit, includes a personalized prevention plan of service (pps), subsequent visit	19	19	$321.00	$96.85
20552 Injections of trigger points in 1 or 2 muscles	14	12	$153.00	$46.85
94640 Inhalation treatment for airway obstruction or sputum production	13	12	$54.00	$13.92
93000 Routine ekg using at least 12 leads including interpretation and report	12	12	$51.00	$14.29

Medical Specialties & State Licenses

CMS Verified: 2026-06-16

Physician Assistant Primary Specialty

NUCC Taxonomy Code: 363A00000X

State License FL PA9106109

A physician assistant is a person who has successfully completed an accredited education program for physician assistant, is licensed by the state and is practicing within the scope of that license. Physician assistants are formally trained to perform many of the routine, time-consuming tasks a physician can do. In some states, they may prescribe medications. They take medical histories, perform physical exams, order lab tests and x-rays, and give inoculations. Most states require that they work under the supervision of a physician.

Physician Assistant

NUCC Taxonomy Code: 363A00000X

Hospital & Practice Group Affiliations

Legacy Healthcare Services Inc

17470 Brookside Trace Ct, Tampa, FL 336476201

Phone: 8134435042

Zephyrhills Family Practice And Geriatric Care Llc

7213 Green Slope Dr, Zephyrhills, FL 335411306

Phone: 8137150165

Practice Associates & Co-Workers

Healthcare professionals and specialists practicing at this location or sharing practice phone/fax

4 Associated Practitioners

Calvin Zhang , PA-C

Physician Assistant

NPI 1013744051

Physician Assistant (Certified)

Dr. Joseph Nystrom , MD

Family Medicine

NPI 1629006127

Doctor of Medicine (M.D.)

Dr. Harry Blackstone , DO

Family Medicine

NPI 1720016496

Doctor of Osteopathic Medicine (D.O.)

Roland Mckendree , ARNP

Nurse Practitioner - Family

NPI 1841639945

Advanced Registered Nurse Practitioner

Career & Practice History Timeline

Chronological log of verified NPI updates, location relocations, credentials, and registry changes

10 Historical Events

👤

Provider Name / Credentials Updated March 20, 2020

Recorded as MARISSA WILLIAMS, PA-C

📍

Updated Practice Location April 06, 2018

Registered at 7213 GREEN SLOPE DR, ZEPHYRHILLS, FL 335411306 (Tel: 8133554914)

📍

Updated Business Mailing Address April 06, 2018

Registered at 7213 GREEN SLOPE DR, ZEPHYRHILLS, FL 335411306 (Tel: 8133554914)

🎓

Medical Taxonomy / Specialty Registered (Primary Specialty) April 06, 2018

Physician Assistant

✅

NPI Profile Active July 15, 2016

NPI status registered as active in NPPES database

📍

Updated Practice Location July 15, 2016

Registered at 13933 17TH STREET, SUITE 101, DADE CITY, FL 33525 (Tel: 3525676763)

📍

Updated Business Mailing Address July 15, 2016

Registered at 13933 17TH STREET, SUITE 101, DADE CITY, FL 33525 (Tel: 3525676763)

👤

Provider Name / Credentials Updated July 15, 2016

Recorded as MARISSA NAGY, PA-C

🎓

Medical Taxonomy / Specialty Registered (Primary Specialty) July 15, 2016

Physician Assistant (License #PA9106109 in FL)

🟢

Initial NPI Registration & Enumeration June 29, 2011

First registered as active Individual Practitioner in NPPES Database.

Patient & Community Reviews

Verified patient ratings, medical care experiences, and facility photos

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NPI Administrative Meta

NPI Number: 1851688873

Entity Type:

Individual Provider Physician, Nurse Practitioner, or Solo Healthcare Professional (Type 1 NPI)

Enumeration Date: June 29, 2011

Last Update: June 16, 2026

Sole Proprietor: No

Update or Correct Profile

Mailing Address

7213 Green Slope Dr

Zephyrhills, FL 335411306

Phone: 8133554914

Public Domain Record This profile contains public domain information published by CMS and NPPES under the Freedom of Information Act (FOIA).

⚠️ Medical Disclaimer

This directory listing is for informational purposes only and does not constitute medical advice, diagnosis, or physician endorsement. If you are experiencing a medical emergency, please call 911 immediately.