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Data Sources: Centers for Medicare & Medicaid Services (CMS), Medicare Provider Utilization and Payment Data
Disclaimer: This site is an independent journalism project. Data analysis and editorial content are not affiliated with or endorsed by CMS or any government agency. All spending figures are based on publicly available Medicare payment records.
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Methodology•Download Data
  1. Home
  2. Providers
  3. Robert Zajac
⚕️
MDIndividual

Robert Zajac, MD

NPI: 1013907963
San Antonio, TX
10 years of data
Infectious Disease
$16.6M
Total Payments
154
Beneficiaries
334.2K
Services
5.2x
Markup Ratio

Peer Comparison

99th
percentile in specialty
This provider$16.6M
Specialty median$93.3K

📋 Key Findings

1Billed $16.6M over 10 years
25.2x markup ratio (above median)
399th percentile in Infectious Disease by payments
4134 services/day — unusually high
5Payments surged 167% in 2019
67 procedures with >3x markup

This provider averages 134 services per working day

Based on 334.2K total services over 10 years (250 working days/year). Learn about impossible service volumes →

🔎 Data Analysis

This provider's $16.6M in total Medicare payments ranks in the 99th percentile of Infectious Disease providers nationally.

Their average markup ratio of 5.2x is significantly above the specialty median of 2.8x.

Averaging 134 services per working day raises questions about billing patterns.

Medicare payments to this provider grew 536% from 2014 to 2023.

AI-generated analysis based on Medicare payment data.

Annual Medicare Payments

Annual Services Provided

Avg Payment per Service

Markup Ratio Over Time

📈

Notable: Payments increased 167% in 2019

Year-over-year payment surges can indicate changes in practice volume, new services, or billing pattern shifts.

Submitted Charges vs. Medicare Payments

Average per-service amounts submitted by the provider compared to what Medicare actually paid — the gap represents the markup.

YearAvg SubmittedAvg PaidMarkup RatioGap per ServiceTotal PaymentsServicesBeneficiaries
2014$179.36$34.425.21x$144.94$495.1K14.4K15
2015$165.63$32.635.08x$133.00$629.3K19.3K16
2016$166.81$35.974.64x$130.84$595.2K16.5K11
2017$162.23$31.675.12x$130.56$861.4K27.2K12
2018$160.83$32.944.88x$127.89$1.2M36.9K15
2019$273.18$64.224.25x$208.96$3.2M50.5K20
2020$333.21$65.775.07x$267.44$2.5M37.6K18
2021$265.03$46.505.70x$218.53$2.0M42.3K17
2022$360.56$67.025.38x$293.54$1.9M29.0K15
2023$320.43$52.126.15x$268.31$3.1M60.4K15

Top Procedures (20)

J1599Injection, immune globulin, intravenous, non-lyophilized (e.g., liquid), not otherwise specified, 500 mg⚠ 5.1x markup
$6.4M
74.4K services$86.53/svc5.09x markup
J1561Injection, immune globulin, (gamunex-c/gammaked), non-lyophilized (e.g., liquid), 500 mg⚠ 7.2x markup
$3.1M
82.1K services$37.99/svc7.15x markup
J1566Injection, immune globulin, intravenous, lyophilized (e.g., powder), not otherwise specified, 500 mg⚠ 5.9x markup
$2.9M
105.8K services$27.42/svc5.88x markup
J1556Injection, immune globulin (bivigam), 500 mg⚠ 4.3x markup
$1.6M
28.1K services$55.86/svc4.33x markup
99214Established patient office or other outpatient visit, 30-39 minutes
$576.5K
7.7K services$74.81/svc2.86x markup
99232Subsequent hospital care with moderate levelof medical decision making, if using time, at least 35 minutes
$447.2K
8.1K services$55.20/svc2.62x markup
99223Initial hospital care with moderate level of medical decision making, if using time, at least 75 minutes
$443.6K
2.9K services$150.85/svc2.68x markup
99233Subsequent hospital care with moderate levelof medical decision making, if using time, at least 50 minutes
$354.5K
4.4K services$80.87/svc2.56x markup
96365Infusion into a vein for therapy, prevention, or diagnosis, 1 hour or less⚠ 3.1x markup
$196.6K
3.7K services$52.56/svc3.11x markup
96366Infusion into a vein for therapy, prevention, or diagnosis, each additional hour⚠ 4.6x markup
$160.0K
10.0K services$16.04/svc4.56x markup
99215Established patient office or other outpatient visit, 40-54 minutes
$97.2K
872 services$111.48/svc2.53x markup
99204New patient office or other outpatient visit, 45-59 minutes
$75.3K
650 services$115.87/svc2.85x markup
99213Established patient outpatient visit, total time 20-29 minutes
$58.5K
1.1K services$53.50/svc2.65x markup
36589Removal of central venous catheter for infusion
$27.7K
232 services$119.26/svc2.71x markup
G0181Physician or allowed practitioner supervision of a patient receiving medicare-covered services provided by a participating home health agency (patient not present) requiring complex and multidisciplinary care modalities involving regular physician or allow
$19.3K
240 services$80.46/svc2.70x markup
99222Initial hospital care with straightforward or low-level medical decision making, if using time, at least 55 minutes
$16.2K
158 services$102.74/svc2.61x markup
G0180Physician or allowed practitioner certification for medicare-covered home health services under a home health plan of care (patient not present), including contacts with home health agency and review of reports of patient status required by physicians and
$16.1K
408 services$39.40/svc2.65x markup
96375Injection of additional new drug or substance into vein⚠ 9.2x markup
$16.1K
1.3K services$12.66/svc9.24x markup
99443Telephone medical discussion with physician, 21-30 minutes
$10.1K
108 services$93.23/svc2.31x markup
99231Subsequent hospital care with straightforward or low level of medical decision making, per day, if using time, at least 25 minutes
$10.0K
323 services$30.89/svc2.52x markup
Show detailed table ▾
CodeDescriptionServicesPaymentsAvg/ServiceMarkup
J1599Injection, immune globulin, intravenous, non-lyophilized (e.g., liquid), not otherwise specified, 500 mg74.4K$6.4M$86.535.09x
J1561Injection, immune globulin, (gamunex-c/gammaked), non-lyophilized (e.g., liquid), 500 mg82.1K$3.1M$37.997.15x
J1566Injection, immune globulin, intravenous, lyophilized (e.g., powder), not otherwise specified, 500 mg105.8K$2.9M$27.425.88x
J1556Injection, immune globulin (bivigam), 500 mg28.1K$1.6M$55.864.33x
99214Established patient office or other outpatient visit, 30-39 minutes7.7K$576.5K$74.812.86x
99232Subsequent hospital care with moderate levelof medical decision making, if using time, at least 35 minutes8.1K$447.2K$55.202.62x
99223Initial hospital care with moderate level of medical decision making, if using time, at least 75 minutes2.9K$443.6K$150.852.68x
99233Subsequent hospital care with moderate levelof medical decision making, if using time, at least 50 minutes4.4K$354.5K$80.872.56x
96365Infusion into a vein for therapy, prevention, or diagnosis, 1 hour or less3.7K$196.6K$52.563.11x
96366Infusion into a vein for therapy, prevention, or diagnosis, each additional hour10.0K$160.0K$16.044.56x
99215Established patient office or other outpatient visit, 40-54 minutes872$97.2K$111.482.53x
99204New patient office or other outpatient visit, 45-59 minutes650$75.3K$115.872.85x
99213Established patient outpatient visit, total time 20-29 minutes1.1K$58.5K$53.502.65x
36589Removal of central venous catheter for infusion232$27.7K$119.262.71x
G0181Physician or allowed practitioner supervision of a patient receiving medicare-covered services provided by a participating home health agency (patient not present) requiring complex and multidisciplinary care modalities involving regular physician or allow240$19.3K$80.462.70x
99222Initial hospital care with straightforward or low-level medical decision making, if using time, at least 55 minutes158$16.2K$102.742.61x
G0180Physician or allowed practitioner certification for medicare-covered home health services under a home health plan of care (patient not present), including contacts with home health agency and review of reports of patient status required by physicians and408$16.1K$39.402.65x
96375Injection of additional new drug or substance into vein1.3K$16.1K$12.669.24x
99443Telephone medical discussion with physician, 21-30 minutes108$10.1K$93.232.31x
99231Subsequent hospital care with straightforward or low level of medical decision making, per day, if using time, at least 25 minutes323$10.0K$30.892.52x

Markup Analysis

Charge-to-Payment Ratio

5.2x

This provider submits charges 5.2 times higher than what Medicare actually pays.

What This Means

A markup ratio of 5.2x means for every $100 Medicare pays, this provider initially charges $520. This is higher than the national average.

Location

San Antonio, TX

Provider Verification

Always verify provider credentials and location before scheduling appointments. This data reflects Medicare payments and may not include all practice locations.

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Data Sources

  • • Centers for Medicare & Medicaid Services (CMS)
  • • Medicare Provider Utilization and Payment Data (2014-2023)
  • • National Plan and Provider Enumeration System (NPPES)

Last Updated: February 2026 (data through 2023, the latest CMS release)

Note: All data is from publicly available Medicare records. OpenMedicare is an independent journalism project not affiliated with CMS.

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