Dermatology Billing Services / 2026 NCCI

Mohs, Path, and Repair on One Date. Where It Unbundles, Where It Doesn't.

Lead with this: when the same physician performs Mohs micrographic surgery (17311 to 17315), the microscopic pathology is already inside the code. You do not add a surgical pathology line for those same-session frozen sections. Repair is separate and payable. A same-day E/M needs a clean modifier 25 story. Everything else is decided by the NCCI PTP edits, and modifiers 59 or X{EPSU} only unbundle a service that is genuinely distinct.

Mohs CPT codes in the family: 17311, 17312, 17313, 17314, 17315

000

Global-day period on Mohs codes under the CY2026 PFS, so a same-day E/M is not auto-bundled

25 / 59

The two modifiers auditors scrutinize most on a Mohs date of service

Surgeon acting as both operator and pathologist, which is exactly why the path bundles

The three services on the claim

One date, three questions. Each one has its own answer.

A Mohs day usually carries three billable ideas: the staged excision, the tissue examination, and the closure. They do not share a fate. Read each on its own.

17311 to 17315

The Mohs stages

17311 (head, neck, hands, feet, genitalia) or 17313 (trunk, arms, legs) for the first stage, then +17312 / +17314 per additional stage, and +17315 for blocks beyond the fifth in a stage. The code bundles the excision, mapping, and microscopic read.

Bill by stage and block, per lesion

88302 to 88305 / 88331

Same-session pathology

The Mohs surgeon is the pathologist. Frozen-section interpretation of the Mohs tissue is included. Reporting 88302 to 88305 or 88331 for those same specimens is the classic unbundling denial.

Bundled into Mohs. Do not add

12001 to 14302 / grafts

The repair

Mohs does not include closure. Intermediate and complex repair, adjacent tissue transfer, flaps, and grafts are separately reportable when documented, sized, and site-matched.

Separately payable when documented

From the coding floor

What the coders actually say

Senior Mohs coder

Multi-site dermatology group

If my Mohs surgeon read the frozen section, that pathology is already paid inside 17311. Adding 88305 is not a gray area, it is a takeback waiting to happen.

CPT builds the pathologic examination into the Mohs family, and the NCCI PTP edits pair the same-session surgical pathology codes as bundled. The exception is narrow: a separately obtained specimen read by a different provider, such as a diagnostic biopsy on a prior date or a different lesion, can carry its own path line.

Derm AR team lead

Repair and closure denials

The repair is where we leave money on the table, not where we overbill. Closure is separate from Mohs. The trick is proving the closure type with a measured, documented note.

Intermediate repair, complex repair, and adjacent tissue transfer are not included in the Mohs codes. When an NCCI PTP edit fires between a closure and a tissue transfer at the same site, resolve it with documentation and the correct modifier, never a reflexive 59 on every line.

Audit reviewer

Payer and internal QA

Modifier 25 is not a checkbox. If the only reason the patient walked in was the scheduled Mohs, there is no separate E/M to append it to.

Mohs codes carry a 000-day global, so a same-day E/M is allowed only when it is significant and separately identifiable from the procedure. A new problem, a distinct evaluation, a different lesion decision. The CY2026 PFS and the NCCI policy manual both reward a note that stands on its own.

Clean vs. bundled

Same-day pathology: the scenarios that split the claim

Same physician plus same specimen is the bundle. Change the provider or the specimen and the picture changes. Here is the line coders draw.

Scenario on the Mohs date	Path separately billable?	Why
Mohs surgeon reads frozen sections of the Mohs tissue	Bundled	Microscopic exam is included in 17311 to 17315. NCCI PTP pairs the same-session path as inclusive.
Debulk or curettage specimen sent for routine permanent path, read by a separate pathologist	If distinct	A genuinely separate specimen and interpreter may support 88304 or 88305, documented and modifier-supported.
Diagnostic biopsy of a different lesion, same visit	Separate	Different lesion, different service. Distinguish with the appropriate X{EPSU} or 59 and clear site documentation.
Special stains added to confirm Mohs margins	Bundled	Stains supporting the Mohs margin read remain part of the Mohs work, not a separate 88342 line.
Repair, flap, or graft after the final Mohs stage	Separate	Closure is never inside Mohs. Report the repair family that matches the documented type and size.

Modifier decoder

25, 59, and the X set. Use the smallest hammer that fits.

Significant, separately identifiable E/M

Appended to the E/M, not the procedure, when a distinct evaluation happens on the Mohs date. The note must justify an evaluation beyond the procedure itself.

Auto-appending 25 to every Mohs-day visit is the fastest way to draw a prepay edit.

Distinct procedural service

Unbundles an NCCI PTP pair only when the services are truly separate: different lesion, different session, different site. The last resort when no X modifier is more specific.

59 does not make a bundled same-session path line payable. It is not a bypass for included work.

XEPSU

The precise subset of 59

XE separate encounter, XS separate structure, XP separate practitioner, XU unusual non-overlapping service. Payers increasingly prefer these over a blanket 59.

Pick the X that matches the fact pattern. A wrong-fit X reads as guessing to an auditor.

The NCCI PTP decision, in three gates

Run every Mohs-day line pair through this before a modifier ever goes on the claim.

Gate 1

Is there a PTP edit between the two codes?

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Gate 2

Modifier indicator 0 means never unbundle. 1 means only with documentation.

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Gate 3

Is the service truly distinct by encounter, structure, practitioner, or lesion?

2026 guidelines this page is built on

CMS Medicare Physician Fee Schedule, CY2026 final rule, for global periods and payment policy on 17311 to 17315.
AMA CPT 2026, Mohs micrographic surgery codes 17311, 17312, 17313, 17314, 17315 and their bundled pathologic examination.
National Correct Coding Initiative (NCCI) PTP edits and Policy Manual, 2026 edition, on same-session pathology and modifier indicators.
CMS modifier guidance for 25, 59, and the X{EPSU} subset (XE, XS, XP, XU).
CPT integumentary repair guidelines, simple, intermediate, complex repair, adjacent tissue transfer, flaps, and grafts as services separate from Mohs.
Surgical pathology codes 88302 to 88305 and 88331, evaluated against the same-physician, same-specimen rule.

Stop giving back Mohs revenue you earned, and stop appending modifiers you cannot defend.

ASP-RCM builds the edit logic into your dermatology billing services workflow: NCCI PTP screening before the claim leaves, closure captured at the correct repair tier, and a modifier 25 and 59 story your auditor will accept. Fewer takebacks on the path lines, more paid on the repair lines.

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