Allergy and immunology practices have a billing profile that's unlike most specialties. You're often running allergy testing, mixing and administering immunotherapy, and managing complex patients across multiple visits, each with its own documentation and coding requirements. Antigen preparation and injection billing is a large revenue line for an allergy practice, which is exactly why unit-count errors on 95165 and 95004 get expensive fast.
If you're working through these issues, our specialty billing services can help you address them systematically.
Percutaneous (scratch/prick) testing uses CPT 95004, and intradermal testing uses 95024 (single) or 95027 (sequential). These are unit-based codes: you bill per test administered. The key documentation requirement: record each allergen tested, the technique used, and the reaction result. Without this, payers will deny or downcode.
One thing that trips practices up: billing both scratch and intradermal for the same allergen on the same day. Some payers consider this a duplicate. Know your payer policies before you bill both methods together.
This is where allergy practices make real money, and where billing errors are most expensive. The codes break down like this:
The 95165 code is billed in units, one unit per dose, up to the total doses prepared. Practices sometimes bill the wrong unit count or forget that this code is for professional services only, not the antigen itself. 95165 is billed per dose, so a unit-counting error repeats across every refill.
When your practice mixes the antigen, that preparation is a separately billable service. But the documentation has to reflect it; what was prepared, the concentration, the lot numbers, and who supervised the preparation. If your allergist isn't directly involved in preparation oversight, you may not be able to bill the professional component.
Sublingual immunotherapy (SLIT) doesn't have its own dedicated CPT, most practices use an unlisted code or bill it under evaluation and management. Subcutaneous immunotherapy (SCIT) has established codes. The distinction matters because SLIT reimbursement is inconsistent across payers, and some don't cover it at all.
Check your payer contracts before offering SLIT as a covered service. Billing for it and then eating the denial is a cash flow problem that compounds over months.
You can bill an E&M on the same day as immunotherapy if a separately identifiable service is provided. Use modifier -25. The E&M must be documented independently; you can't use the immunotherapy visit note as your E&M documentation. Payers watch for this.
Many allergy/immunology practices perform in-office spirometry (CPT 94010). When you're also doing allergy testing the same day, confirm that both services are independently documented and medically necessary. Some payers bundle these and won't pay both without a strong clinical rationale in the notes.
| Service | Must Document |
|---|---|
| Allergy skin testing | Each allergen, technique, reaction result, interpretation |
| Immunotherapy injection | Allergen administered, dose, site, observation time, any reactions |
| Antigen preparation (95165) | Antigens mixed, concentrations, number of doses, supervising physician |
| E&M on injection day | Separate problem-focused note; modifier -25 on E&M claim |
Allergy billing rewards detail. Practices with clean documentation consistently outperform on collections, and survive audits without scrambling for records they should have had all along.
See how Rcmaxis handles the full scope of Allergy & Immunology billing on our Allergy & Immunology billing services page.
Allergy practices get reviewed on volume. Testing and immunotherapy are unit-based, so a practice that bills 95004 or 95165 in high counts stands out against its peers. Auditors ask a simple question: can every unit you billed be traced to a documented allergen, dose, and result? If the chart shows a panel result but not each allergen tested, the units above what's documented are at risk.
Antigen preparation is the second pressure point. Billing 95165 means you can show what was mixed, the concentration, the lot numbers, and who supervised the preparation. Payers and Medicare contractors can look back three years, and they can extrapolate a sample error rate across every claim in that window, so a documentation gap on a few dozen vials can turn into a much bigger repayment demand.
Allergy skin testing generates units, and every unit needs a record. A good template lists each allergen tested, the method, the wheal and flare results, and the controls. It also records the time the reading was taken and who did it. If the template doesn't require those fields, providers will skip them on busy days.
Build a template that won't let the note close until the number of tests documented matches the number billed. That single control catches most unit errors before they leave the building, and it gives a reviewer exactly what they'll ask for.
Injection visits are quick, but the notes need to carry the essentials: the patient, the vial and its lot, the dose, the site, the time of injection, the observation period, and any reaction. Track each patient's dosing schedule so that increases, missed doses, and dose reductions after a gap are recorded and safe. That record is both a clinical safeguard and the basis for the claim.
For antigen preparation, keep a compounding log: what was mixed, when, by whom, under whose supervision, and which patient the vial belongs to. When the log and the claims agree, prep billing is straightforward to defend.
Allergy denials often cluster by payer. One plan may reject same-day E/M with immunotherapy, another may limit testing units, and another may require a specific diagnosis. Sort your denials by payer once a quarter, look for the repeat reasons, and write a one-line rule for each. Then load those rules into the scrubber so the claim is corrected before it goes out.
Match your antigen preparation records against what you billed each month. Each vial prepared should have a corresponding claim, and each claim should have a record of preparation. Differences point to missed revenue or unsupported billing, and both are worth fixing.
Allergy revenue is a volume game made of small numbers. A single antigen therapy service under 95165 pays $17.37 in the office, and a percutaneous test unit under 95004 pays $3.67. That sounds like pocket change until you multiply it: a practice that does 40 tests per patient on 25 new patients a month is billing 1,000 test units, worth $3,670 a month at the Medicare rate.
Now take the 5% of units that go out with the wrong count or no medical necessity link. That's 50 units, about $184 a month. It looks small, but the real cost is the time spent reworking claims at roughly 20 minutes each. Count the units at the point of care, and the error rate drops before the claim is ever built.
Yes, but only when a separately identifiable service is provided and you append modifier 25. The E/M has to be documented on its own. You can't use the immunotherapy injection note as the evaluation and management documentation.
Per test. Percutaneous testing (95004) and intradermal testing (95024 and 95027) are unit-based, so you bill the number of tests actually administered, and the chart needs to record each allergen, the technique, and the reaction result.
Yes, when your practice prepares the antigen. The documentation has to show what was prepared, the concentration, lot numbers, and who supervised. Without that record, the prep units can't be supported on review.
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