CPT 17315Surgery

Mohs surg addl block

CPT code 17315 represents the work done by a surgeon to examine each additional tissue block during Mohs micrographic surgery, a specialized skin cancer removal technique. This is an add-on code billed for each extra block of tissue examined beyond the first stage covered by a different code.

Showing rates for

National Average

Base Medicare rate

$78.28

This calculator gives a typical-case estimate using standard Medicare modifier rules. Actual payment depends on payer policies, documentation, code-specific CMS status indicators, and locality. Verify before billing.

RVU breakdown

Work RVU

0.87

PE RVU (NF)

1.47

MP RVU

0.08

Total RVU

2.42

Conversion factor: 32.3465 · Source: CMS MPFS RVU25A · Confidence: High

NCCI bundling edits

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Billing tips

Bill one unit of 17315 for each additional block examined beyond the first stage, not per tissue section
Impact: Prevents underbilling; average Mohs case requires 2-4 blocks, representing $156.56-$313.12 in additional non-facility revenue
Document the specific number of blocks, tissue locations, and margin status for each block in the operative report
Impact: Reduces audit risk and supports medical necessity; missing block counts are the #1 reason for post-payment audits
Never bill 17315 alone; it must be billed with a primary Mohs code (17311-17314) from the same session
Impact: Standalone billing results in 100% denial as this is an add-on code; requires primary procedure for payment
For non-facility settings, ensure place of service code 11 is used to receive the higher $78.28 rate versus $47.87 facility rate
Impact: Difference of $30.41 per block; for 3-block case this represents $91.23 additional revenue
Track RVUs separately as 17315 contributes 2.42 RVUs per block toward physician productivity metrics
Impact: Multi-block cases can generate 7-12 total RVUs; important for MIPS reporting and compensation models
Bill on the same claim form as the primary Mohs code with careful attention to unit counts matching documented blocks
Impact: Separate claims may trigger edits; unified claims process faster and reduce the 15-20% error rate seen with split billing

Common denials

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Frequently asked questions

What is CPT code 17315 used for?

CPT 17315 is an add-on code used to bill for each additional tissue block examined during Mohs micrographic surgery beyond the first stage. It represents the physician work of preparing, examining, and interpreting frozen sections from each additional tissue block to assess cancer margins.

How much does Medicare pay for CPT 17315 in 2025?

Medicare pays $78.28 for CPT 17315 in non-facility settings and $47.87 in facility settings based on the 2025 national average rates. Actual payment may vary by geographic locality using MAC-specific adjustments.

Can CPT 17315 be billed alone?

No, CPT 17315 is an add-on code and cannot be billed alone. It must always be billed with a primary Mohs surgery code (17311, 17312, 17313, or 17314) from the same session. Billing 17315 without a primary code will result in denial.

How many times can you bill CPT 17315 per session?

CPT 17315 can be billed multiple times per session based on the actual number of additional tissue blocks examined. There is no specific limit, but each unit must be supported by documentation showing a distinct tissue block was prepared and examined. Most cases involve 2-4 additional blocks.

What documentation is required for billing CPT 17315?

Documentation must include the total number of blocks examined, anatomic location and mapping of each block, frozen section findings, margin status, medical necessity for additional blocks, and physician interpretation. Block counts must be clearly stated in the operative report to support units billed.

What is the RVU value for CPT 17315?

CPT 17315 has a total RVU of 2.42, consisting of 0.87 work RVU, 1.47 non-facility practice expense RVU (0.53 facility PE RVU), and 0.08 malpractice RVU based on the 2025 Medicare Physician Fee Schedule.

What is the difference between CPT 17315 and 17311?

CPT 17311 is the primary code for the first stage of Mohs surgery including up to 5 tissue blocks, while CPT 17315 is an add-on code for each additional block examined beyond the first stage. 17311 includes the initial tumor removal and first-level examination; 17315 captures work for subsequent blocks when margins are positive.