Comparison of Add-On Code Guidelines

May 4th, 2021 - Wyn Staheli, Director of Research

Categories: CPT^® Coding

Add-on codes are codes that are not intended to be reported alone. They are reported with another primary procedure to identify that additional services have been provided in conjunction with that primary procedure. Generally, they include the words “List separately in addition to code.” Interestingly, there are some differences in the instructions/guidelines regarding the use of these codes in the CPT® codebook, the NCCI Policy Manual, and on the CMS website. This article outlines the differences between each of these.

Note: Individual payers may choose to follow guidelines from CPT, NCCI, CMS, or use their own so be sure to understand the add-on code guidelines for the payers that your organization is billing. It is recommended that you include that information in your organization’s Policies and Procedures Manual.

CPT Codebook Add-on Code Information

The CPT codebook guidelines are those that most of us are familiar with. It states the following (emphasis added):

Some of the listed procedures are commonly carried out in addition to the primary procedure performed. These additional or supplemental procedures are designated as “add-on” codes with the + symbol. Add-on codes in CPT 2021 can be readily identified by specific descriptor nomenclature which includes phrases such as “each additional” or “(List separately in addition to primary procedure).”

The add-on code concept … applies only to add-on procedures or services performed by the same physician. Add-on codes describe additional intra-service work associated with the primary procedure, eg, additional digit(s), lesion(s)...

Add-on codes are always performed in addition to the primary service or procedure and must never be reported as a stand-alone code. When the procedure may be reported bilaterally, the appropriate add-on code is reported twice, unless the code descriptor, guidelines, or parenthetical instructions for that particular add-on code instructs otherwise. Do not report modifier 50 Bilateral procedures, in conjunction with add-on codes. All add-on codes in the CPT code set are exempt from the multiple procedure concept.

— CPT codebook, Instructions for Use of the CPT Codebook

There are a few things to note within these guidelines:

Review additional instructions, guidelines and parenthetical instructions to identify acceptable primary codes for the add-on code, as some add-on codes may apply to multiple primary codes
While an add-on code must NEVER be reported as a stand-alone code, according to CMS guidelines (as noted below) an add-on code reported without a primary code is rarely eligible for payment if it is the only procedure reported by a practitioner.
Be aware of individual payer edits that may disallow the add-on code if the primary service was performed by another provider on the same day.

NCCI Policy Manual Add-on Code Statement

The NCCI Policy Manual states the following about add-on codes (emphasis added):

Some codes in the "CPT Manual" are identified as “add-on” codes (AOCs), which describe a service that can only be reported in addition to a primary procedure. "CPT Manual" instructions specify the primary procedure code(s) for most AOCs. For other AOCs, the primary procedure code(s) is (are) not specified. When the "CPT Manual" identifies specific primary codes, the AOCs shall not be reported as a supplemental service for other HCPCS/CPT codes not listed as a primary code.

AOCs permit the reporting of significant supplemental services commonly performed in addition to the primary procedure. By contrast, incidental services that are necessary to accomplish the primary procedure (e.g., lysis of adhesions in the course of an open cholecystectomy) are not separately reportable with an AOC. Similarly, complications inherent in an invasive procedure occurring during the procedure are not separately reportable. For example, control of bleeding during an invasive procedure is considered part of the procedure and is not separately reportable.

In general, NCCI [Procedure to Procedure] PTP edits do not include edits with most AOCs because edits related to the primary procedure(s) are adequate to prevent inappropriate payment for an add-on coded procedure (i.e., if an edit prevents payment of the primary procedure code, the AOC shall not be paid). However, NCCI does include edits for some AOCs when coding edits related to the primary procedures must be supplemented. Examples include edits with add-on HCPCS/CPT codes 69990 (Microsurgical techniques requiring use of operating microscope) and 95940/95941/G0453 (Intraoperative neurophysiology testing).

— NCCI Policy Manual, Chapter 1

The following are some additional CMS NCCI Policy Manual Guidelines:

CPT add-on codes may only be reported with CPT primary codes (always review the instructions at the code level for coding accuracy).
HCPCS add-on codes may only be reported with HCPCS primary codes (always review the instructions at the code level for coding accuracy)
Supplemental services refer to add-on codes, which are NOT the same as incidental or bundled services
Procedure-to-procedure (PTP) edits do not identify the primary procedures that link to specific add-on codes
If the primary procedure is non-covered, the add-on service is also non-covered.

Medicare Add-on Code Guidelines

Medicare goes even further than the CPT codebook or the NCCI Policy Manual as noted in the following statement (emphasis added):

An AOC is a HCPCS/CPT code that describes a service that, with rare exception, is performed in conjunction with another primary service by the same practitioner. An AOC is rarely eligible for payment if it is the only procedure reported by a practitioner.

Add-on codes may be identified in three ways:

The code is ... a Type I, Type II, or Type III add-on code.
On the Medicare Physician Fee Schedule Database an add-on code generally has a global surgery period of "ZZZ".
In the CPT Manual an add-on code is designated by the symbol "+". The code descriptor of an add-on code generally includes phrases such as "each additional" or "(List separately in addition to primary procedure)."

CMS has divided the add-on codes into three groups to distinguish the payment policy for each group.

Type I - A Type I add-on code has a limited number of identifiable primary procedure codes. The CR lists the Type I add-on codes with their acceptable primary procedure codes. A Type I add-on code, with one exception, is eligible for payment if one of the listed primary procedure codes is also eligible for payment to the same practitioner for the same patient on the same date of service. Claims processing contractors must adopt edits to assure that Type I add-on codes are never paid unless a listed primary procedure code is also paid.
Type II - A Type II add-on code does not have a specific list of primary procedure codes. The CR lists the Type II add-on codes without any primary procedure codes. Claims processing contractors are encouraged to develop their own lists of primary procedure codes for this type of add-on codes. Like the Type I add-on codes, a Type II add-on code is eligible for payment if an acceptable primary procedure code as determined by the claims processing contractor is also eligible for payment to the same practitioner for the same patient on the same date of service.

Type III - A Type III add-on code has some, but not all, specific primary procedure codes identified in the CPT Manual. The CR lists the Type III add-on codes with the primary procedure codes that are specifically identifiable. However, claims processing contractors are advised that these lists are not exclusive and there are other acceptable primary procedure codes for add-on codes in this Type. Claims processing contractors are encouraged to develop their own lists of additional primary procedure codes for this group of add-on codes. Like the Type I add-on codes, a Type III add-on code is eligible for payment if an acceptable primary procedure code as determined by the claims processing contractor is also eligible for payment to the same practitioner for the same patient on the same date of service.

— CMS.gov

These guidelines from CMS provide even more guidance; however, as noted in the statements in bold above, for Type II and Type III add-on codes, individual Medicare Administrative Contractors (MACs) are encouraged to create their own lists of which procedure codes may be reported with them. Thus, in many cases, providers must resort to reviewing published payer policies to determine which add-on codes may be reported with which primary procedure codes. However, FindACode.com subscribers do have access to the following helpful information:

Global Surgery Period information: If you look at the “Dashboard” you can see the Global Days right there. If you see “ZZZ”, then Medicare considers it an ‘add-on’ code and all the above rules apply. It can also be viewed (along with other information) by clicking on the [Additional Code Information] bar.
LCD/NCD/Articles: The “Dashboard” also shows if there are Medicare policies that are linked to that code. Click on the “Medicare Policies” to open the [Medicare Policies & Guidelines] bar to review policies linked to that code.
List-A-Code: From this tool, select the code set (i.e., CPT, HCPCS) and then under “Global Days,” select “ZZZ - Code Related to Another Service.” Click [Create list] to view the codes which Medicare defines an add-on code.

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