Mohs Surgery Billing Services

Mohs surgery removes skin cancer one thin layer at a time. The surgeon also reads the tissue slides, which is why this specialty has its own coding rules. A single case can involve several stages, many tissue blocks, and a repair, and each piece is counted differently.

Mohs billing is easy to get wrong. Codes depend on the body area, the stage, and the number of blocks. Repair is billed separately and has its own rules. Westmont connects Mohs surgeons and dermatology practices with vetted billing experts who know how to count stages, link the repair, and support each claim with clear notes.

Who this is for

• Fellowship-trained Mohs surgeons
• Dermatology practices that offer Mohs
• Dermatologic surgery centers
• Surgeons who do Mohs in an office lab
• Referring dermatology groups that share patients
• Practices adding Mohs services

What gets billed

• First stage of Mohs surgery on the head, neck, hands, feet, or genitals
• First stage on the trunk, arms, or legs
• Additional stages when cancer remains
• Additional tissue blocks after the first five in a stage
• Repair after surgery, from simple closure to flaps
• Skin grafts after tumor removal
• Skin biopsies that confirm the cancer
• Evaluation and management visits when separate
• Follow-up skin checks
• Consult visits from referring physicians

Commonly billed codes

Code	Type	What it covers
17311	CPT	Mohs first stage on head, neck, hands, feet, or genitals
17312	CPT	Each added stage in those areas
17313	CPT	Mohs first stage on trunk, arms, or legs
17314	CPT	Each added stage on trunk, arms, or legs
17315	CPT	Each added block after the first five in a stage
13131	CPT	Complex repair of the face or similar area, small size
14040	CPT	Local flap repair on the face, small size
11102	CPT	Skin biopsy by shaving, first lesion
C44.311	ICD-10-CM	Basal cell skin cancer of the nose
C44.92	ICD-10-CM	Squamous cell skin cancer, unspecified site
Z85.828	ICD-10-CM	Personal history of other skin cancer

Note

Codes are examples for orientation, not a complete list, and do not guarantee coverage or payment. Always check current code sets and payer policy.

Billing challenges in Mohs surgery

• Counting stages and blocks. Each stage is a full round of removal and review, and blocks are the pieces of tissue examined. A biller experienced in Mohs counts from the surgeon's map and log, not from memory.
• Body area selection. Codes differ for head and neck versus trunk and limbs. Billers match the code to the exact site in the operative note.
• Pathology is included. The surgeon's own slide reading is part of Mohs, so separate pathology codes for the same tissue are usually denied. Billers avoid duplicate billing, and note when outside pathology applies.
• Repair billing. Repair is generally reported separately by the surgeon who does it, using codes for closure type, size, and site. Billers confirm lengths and layers in the note. If another provider repairs the wound, billing is split.
• Appropriate use criteria. Many payers check whether the tumor type, location, and patient factors meet Mohs criteria. Billers attach the biopsy report and the reason for choosing Mohs.
• Prior authorization. Some payers want approval before surgery. Billers check requirements at scheduling.
• Same-day visit with surgery. A visit on the same day is usually included unless it was a separate, significant service. Billers review notes for modifier 25 support.
• Documentation of site and size. Biopsy site errors are a leading source of problems. Billers cross-check the biopsy and surgery records.

How Westmont can help

• Matching you with vetted billing experts experienced in Mohs and dermatologic surgery
• End-to-end revenue cycle support, from authorization to payment posting
• Denial management for stage count, repair, and appropriate use denials
• Credentialing support for new surgeons and satellite locations
• Charge capture review with your Mohs map and repair notes

Frequently asked questions

How are Mohs stages billed?

The first stage has its own code based on body area. Each later stage is billed with an add-on code for that area. Extra tissue blocks past the first five in a stage use another add-on code. Your note should record each stage and the blocks removed.

Can the surgeon bill pathology for Mohs?

Generally not for the same tissue, because the slide reading is part of Mohs. Separate pathology codes may apply for other tissue, such as a different lesion. Check payer rules and keep records clear about which specimen was which. Ask your biller to flag any case with more than one specimen sent to a lab.

Is the repair billed separately from Mohs?

Usually yes, when the Mohs surgeon performs it. Repair codes depend on the type of closure, size, and site. Records should show length, layers, and technique. If another provider repairs the wound, they bill their own repair. Many payers also set limits on flap and graft codes, so confirm that the size and site match the note.

Why do payers deny Mohs claims?

Common causes include missing biopsy proof, a site that does not meet payer criteria, incorrect stage counts, and duplicate pathology billing. Keeping the biopsy report, map, and notes together prevents most problems. Missing or mismatched site documentation is another frequent reason for payment delays and appeals.

Does Mohs need prior authorization?

Some payers require it and many do not. Rules change, so check each payer's current policy when the case is scheduled. Attach the biopsy report and the reason for choosing Mohs when authorization is needed. Some Medicare contractors publish policy articles on Mohs, so also review your local coverage article.

Related billing services

• Dermatology
• Plastic & Reconstructive Surgery
• Pathology
• Surgical Oncology
• Ambulatory Surgery Centers