skin testing
Allergy Skin Testing CPT Codes (95004, 95024, 95027, 95044): Units, MUEs and the Documentation Behind Them
2026-10-16 · 8 min read
The short answer: the allergy testing codes are paid per test, so
the number of tests you performed goes in the units field, and the chart
has to show that same number of tests, allergen by allergen. For Medicare,
the positive and negative controls are not billable tests. Each code
also carries a daily unit ceiling, the Medically Unlikely Edit (MUE). Above
it, the claim is denied as a coding error, and for most allergy codes you
can appeal with documentation of medical necessity.
This guide pulls those rules together from the ACAAI's practice management
pages, which is where most allergists hear about them first. It is a
documentation aid, not billing advice. CPT is maintained by the American
Medical Association, and your Medicare Administrative Contractor (MAC) and
each commercial payer publish their own policies. Check them.
The codes, in plain terms
The skin-testing codes you'll use most:
- 95004: percutaneous (prick, puncture or scratch) tests with
allergenic extracts, immediate-type reaction. One unit per allergen
tested.
- 95017: percutaneous and intracutaneous tests with venoms.
- 95018: percutaneous and intracutaneous tests with drugs or
biologicals (penicillin testing lives here).
- 95024: intracutaneous (intradermal) tests with allergenic extracts,
immediate-type reaction. One unit per allergen.
- 95027: intracutaneous sequential and incremental tests (end-point
titration). Units follow the number of injections.
- 95028: intracutaneous tests, delayed-type reaction.
- 95044: patch or application tests. One unit per patch.
The ACAAI's guidance on 95004 puts the unit rule simply: the code "is
reported based on the number of individual tests performed", and Medicare
multiplies its single-test payment by the units you report (ACAAI, *95004
Medicare Billing and Coding Guidance*, 2022). The same logic applies across
the family: one test, one unit.
Controls: documented, not billed (Medicare)
Every prick panel has a histamine positive control and a saline negative
control. You must record them, because the panel can't be interpreted
without them. But for Medicare they are not counted as tests. The ACAAI
page explains that the cost of controls is already built into the direct
practice-expense inputs of the testing codes, so a single allergen test
plus its controls is reported as one unit, not three.
Commercial plans vary. Some pay for controls as units and some don't, so
confirm each plan's policy rather than assume.
The MUE table for allergy codes
CMS sets a Medically Unlikely Edit for most codes: the maximum units of
service a provider would report for one patient on one date of service
under most circumstances. The ACAAI's April 2026 update lists these values
for the allergy codes (Medicare and Medicaid, per date of service):
| CPT | What it is | MUE | MAI |
|---|---|---|---|
| 95004 | Percutaneous tests, allergenic extracts | 80 | 3 |
| 95017 | Venom skin testing | 27 | 3 |
| 95018 | Skin testing, drugs and biologicals | 19 | 3 |
| 95024 | Intracutaneous tests, allergenic extracts | 40 | 3 |
| 95027 | Intracutaneous sequential and incremental | 90 | 3 |
| 95028 | Intracutaneous, delayed reaction | 30 | 3 |
| 95044 | Patch test | 90 | 3 |
| 95076 | Ingestion challenge, initial 120 minutes | 1 | 2 |
| 95079 | Ingestion challenge, each additional hour | 2 | 2 |
| 95165 | Multi-dose vial immunotherapy (per dose) | 30 | 3 |
| 95144 | Single-dose vial immunotherapy | 30 | 3 |
| 95145–95149 | Venom immunotherapy (1 to 5 venoms) | 10 each | 3 |
Source: ACAAI, How Many MUEs Can Be Billed in a Day?, updated April 13,
- MUE values change; check the current CMS table before relying on a
number.
The MAI column matters as much as the number. It is the MUE
Adjudication Indicator:
- MAI 3 (most allergy testing codes) is a "date of service" edit based
on clinical judgment. Units above the MUE are denied, but the MAC may pay
them on appeal if the record shows they were medically necessary.
- MAI 2 (the oral food challenge codes) is a policy edit. Units above
the MUE are not payable, and appeal won't change that.
Two more points from the same ACAAI page are worth pinning to the billing
office wall. A denial for exceeding an MUE "is a coding denial, not a
medical necessity denial", and an Advance Beneficiary Notice does not shift
liability for those units to the patient.
For immunotherapy, the ACAAI notes that Medicare defines a dose of 95165 as
1 mL, and that Medicaid definitions vary by state. The College also offers
a sample appeal letter for 95165 units above the MUE.
Above the limit: the panel the history justifies
The MUE of 80 for 95004 is not a target. It is a ceiling. The ACAAI
advocates that payers allow at least 70 prick tests for inhalants and 40
intradermal tests, and it advises checking whether a given payer limits
units for 95004, because many commercial and Medicaid policies set their
own, lower caps.
Beyond the numbers, the test selection has to match the patient. The
Medicare local coverage articles the ACAAI points to (from Palmetto GBA,
First Coast, Noridian, Novitas and WPS) list the ICD-10-CM diagnoses that
support medical necessity for allergy testing. The history in the note
should make the panel look obvious: symptoms, timing, exposures, and the
allergens that plausibly explain them. Our
new patient consult note template
covers how to document that history, and the
covers the diagnosis codes.
What the record has to show
The claim says a number. The chart has to be able to defend it. For every
skin-testing encounter, an auditor will look for:
```
SKIN TESTING RECORD (supports units billed)
Order and indication
- Ordered by: [clinician]; indication: [diagnosis, ICD-10]
- Antihistamines/interfering meds stopped: [drug, date last taken]
Method
- Technique: [percutaneous device / intradermal]; site: [back / volar forearm]
- Extracts: [manufacturer, lot, concentration]
Panel (one line per test = one unit)
Allergen Wheal (mm) Flare (mm) Grade
1 Histamine control [ ] [ ] (control, not billed to Medicare)
2 Saline control [ ] [ ] (control, not billed to Medicare)
3 [allergen] [ ] [ ] [ ]
...
Total allergen tests performed: [n] -> units of 95004 / 95024 / 95044: [n]
Reading
- Read at: [15–20 min]; read by: [name, role]
- Interpretation: [positive / negative per practice grading rules]
Sign-off
- Interpreted and signed by: [allergist], [date/time]
```
The count at the bottom is the line that reconciles the chart and the
claim. If the panel sheet lists 42 allergens and the claim says 48, you
have a problem; if the sheet lists 42 allergens plus two controls and the
Medicare claim says 42, you don't.
For the full documentation standard, including what to record when a test
site wasn't placed or couldn't be read, see the
skin test documentation checklist.
Patch testing has its own reading schedule and scale; see
patch-test reading documentation (ICDRG).
An E/M on the same day
A separate office visit code on the testing date needs its own, separately
identifiable work documented and the appropriate modifier. Payers look
closely at this pairing. If the visit was only to perform and read the
tests, bill the tests.
Where Medora fits
Medora is the AI copilot built only for allergy and immunology practices,
built with a working allergy practice, Allergy Affiliates in Bradenton,
Florida. It does not pick CPT codes or count units. What it does is make
the record that supports them easier to produce.
- Skin testing (investigational): Medora drafts the panel from the
nurse's photos; clinicians confirm every value; the allergist signs. Not
FDA-cleared. The draft asks for the histamine and saline controls first,
flags any site it isn't sure about instead of guessing, says when a site
wasn't photographed, and records nothing as "no reaction" until a person
confirms it. The review screen shows how each result was made (drafted
by Medora, confirmed by the nurse, signed by the clinician) with an audit
trail, which is the chain an auditor wants to see.
- Medora Copilot drafts the allergy visit note from the visit, with a
skin-testing visit template, and suggests ICD-10 codes from the note for
the clinician to review. The diagnosis that justifies the panel ends up
in the same record as the panel.
- Because the modules share one patient context, the clinician sees the
recorded skin-test results (wheal sizes, controls, grades) alongside the
drafted note when reviewing it.
- The clinician reviews, edits and signs every note. Medora doesn't decide
what to test, how many tests to run, or what to bill.
In a 60-day pilot at Allergy Affiliates, the time an allergist spends
signing off each skin-test visit dropped sharply
Frequently asked questions
How many units of 95004 can I bill in a day?
The Medicare MUE for 95004 is 80 units per date of service, with MAI 3.
Units above 80 are denied as a coding error, but the MAC may pay them on
appeal if the record documents medical necessity. Many commercial and
Medicaid plans set lower limits, so check each payer.
Do I bill the histamine and saline controls?
Not to Medicare. The ACAAI explains that control costs are already included
in the practice-expense inputs of the testing codes, so controls are
documented but not reported as units. Commercial payers differ; confirm
each plan.
What are the MUEs for intradermal and patch tests?
Per the ACAAI's April 2026 update: 95024 (intracutaneous, allergenic
extracts) is 40 units, 95027 (sequential and incremental) is 90, and 95044
(patch tests) is 90, all per date of service with MAI 3.
What happens if I exceed the MUE?
The claim line is denied. For MAI 3 codes you can appeal with documentation
of medical necessity. For MAI 2 codes (the oral food challenge codes 95076
and 95079) the excess is not payable. An ABN does not make the patient
liable for MUE-denied units.
Does Medora choose CPT codes or count units?
No. Medora drafts the skin-test panel from the nurse's photos for a person
to confirm, drafts the visit note, and suggests ICD-10 codes for the
clinician to review. Counting, coding and billing stay with your clinicians
and billing team.
Try it on your own visits
- See how Medora handles allergy documentation
- Start the 14-day free trial of Medora Scribe (no card needed)
- Book a demo
- Read the full buyer's guide
- The skin test documentation checklist
- The allergy ICD-10 coding guide
*Sources: ACAAI, "95004 Medicare Billing and Coding Guidance" (June 27,
2022), college.acaai.org/95004-medicare-billing-and-coding-guidance/;
ACAAI, "How Many MUEs Can Be Billed in a Day?" (updated April 13, 2026),
college.acaai.org/how-many-mues-can-be-billed-in-a-day/. CPT® is a
registered trademark of the American Medical Association.*