Add-on codes are special codes listed in the Current Procedural Terminology (CPT) book that may only be used in addition to a primary code when approved by Medicare. A listing in the CPT does not guarantee payment by CMS, because your Medicare Administrative Contractor (MAC) is often the entity that actually determines whether the code is covered and what the payment should be. This review provides a comprehensive look at the various components and instructions for usage for Medicare reimbursement.

MEDICARE’S GUIDELINES vs CPT GUIDELINES

An add-on code is a HCPCS/CPT code that describes a service that is performed in conjunction with another primary service by the same practitioner. It is rarely eligible for payment if it is the only procedure reported by a practitioner.

Add-on codes may be identified in three ways:

1. The code is listed in this Change Request (CR) for subsequent ones as a Type I, Type II, or Type III add-on code (CR is CMS’s way of informing MACs and the interested public regarding changes).
2. On the Medicare Physician Fee Schedule Database (MPFSDB), an add-on code generally has a global surgery period of “ZZZ.” (This means that there is no global period assigned to the code.)
3. In the CPT Manual, an add-on code is designated by the symbol “+.” The 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 individual group.

1. 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 and same session. 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.
2. 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.
3. 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 that 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.

In ophthalmology, you will be using Type I codes for the most part.

CMS will update the list of add-on codes with their primary procedure codes on an annual basis on or by January 1 every year based on changes to the CPT Manual or HCPCS Level II Manual. Quarterly updates will be posted as necessary on April 1, July 1, and October 1 each year. If no changes occur in the add-on code edits for one quarter, no quarterly update will be posted.¹

CPT’s definition states:

“Some of the listed procedures are consistently carried out in addition to the primary procedure performed. These additional or supplemental procedures are designated as add-on codes with the + symbol and they are listed in Appendix D of the CPT code book. Add-on codes apply only to procedures performed by the same physician. Add-on codes describe additional intra-service work associated with the primary procedure, e.g., additional digits, lesions, neurorrhaphy(s), vertebral segment(s), tendon(s), joint(s).

Add-on codes are always performed in addition to the primary service or procedure and must never be reported as a standalone code. When the add-on procedure can be performed bilaterally and is performed 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…”

TIP: Medicare payment rules may differ from other insurers so be sure to brush up on all guidelines.

Example: +0290T (laser corneal incisions) is listed as an add-on code in CPT 2021, but not in the latest CMS list of add-on codes.²

TIP: You will find the CMS Type I coordinates with the CPT definition for add-on codes, which eliminates a lot of worrying and confusion!

CLINICAL APPLICATION: STRABISMUS

Strabismus surgery and Integumentary surgery contain the most add-on codes for ophthalmologists. Add-on codes were developed to compensate surgeons for extra difficulty that may be encountered due to previous surgery, trauma, or various medical conditions. CPT Assistant states, “[add-on codes] cannot stand alone, and do not represent distinct procedures per se…if surgery is performed on both eyes at this operative session and the patient has had previous strabismus surgery, the modifier 50 would be appended to the code describing the surgery.”

The article continues to explain that each eye would have had the primary procedure performed and the add-on procedure in the same session. This applies to codes +67320, +67331, +67332, +67334, +67335, +67340, and +67343.

The MPFSDB has various indicators that are listed in what might be considered unusual places. The indicators for diagnostic tests and sides in surgery are listed in the column entitled “Bilateral Surgery” and use the following system (I know it’s difficult but it has to be mastered):

Bilateral Surgery Indicator provides for services subject to a payment adjustment.

0 = Payment adjustment for bilateral procedures does not apply.

1 = Payment adjustment applies if billed with modifier 50… (payment based on billed amount or 150% of the fee schedule amount).

2 = Payment adjustment does not apply. Payment already based on procedure being a bilateral procedure. Pays 100% of allowable.

3 = Usual payment adjustment does not apply (primarily radiology procedures). Pays 100% of each side.

9 = Concept does not apply.

TIP: Strabismus indicators all have a bilateral indicator of 0 signifying they can only be used once per session per regular CPT code.

TIP: Transposition procedure. CPT Assistant states, “A transposition procedure is performed when a patient has lost functioning in one of the extraocular muscles…An add-on code is not used for minor transpositions of a muscle coincident to a recession or resection.” Transposition procedures are coded when the surgical procedure is performed for correction of a paretic/paralyzed muscle—not for raising or lowering the insertions of muscles for correction of A or V pattern. You may code it once per eye but not per muscle.

CLINICAL APPLICATION: GLAUCOMA MIGS

The rocky road to minimally invasive glaucoma surgery (MIGS) reimbursement should be smoothed out in 2022, when Category I codes are due to replace the Category III Code 0191T. There is still company manufacturer guidance that suggests using Category III code +0376T for additional stents whether they be delivered individually or packaged with multiple stents in an injector. Do not use +0376T for Medicare reimbursement of additional stents. All the MACs consider the code as not medically necessary, and continued use might trigger a closer look at your coding practices.^3,4,5

CLINICAL APPLICATION: OCULOPLASTICS

CPT Codes for oculoplastic surgery are found in both the Eye and Integumentary sections of the CPT Manual. The add-on codes in the Integumentary section are voluminous.

It is more than worthwhile of the surgeon’s time to review the current CPT book and gain awareness of these codes and how to use them.

CONCLUSION

For the most part, it is sufficient to use the CPT as your main resource, while maintaining awareness of the Medicare variations. There are a few other codes that basically have limited application, such as +0290T and +65757, that have minimal utilization. Not using the add-on codes, or using them erroneously, serves only to diminish financial optimization. ■

REFERENCES

1. The references below are taken from the CMS website on Add-on codes.
   • Change Report for 04012021 Add-on Code Edit Changes for Medicare_03022021-REVISED - Posted March 2, 2021 (ZIP)
   • Complete File of Add-on Code Edits for 04012021 Implementation for Medicare_03082021-REVISED - Posted March 10, 2021 (ZIP)
   • Change Report for Add-on Code Edit Changes 01012021 for Medicare - Posted December 1, 2020 (ZIP)
   • Complete File of Add-on Code Edits for 01012021 Implementation for Medicare - Posted December 1, 2020 (ZIP)
2. CMS: see Bullet #2 in above listings.
3. Asbell, R.L.: MIGS 2020: Medicare’s new compliance and reimbursement regulations. The Ophthalmic ASC. February, 2020.
4. Asbell, R.L.: MIGS: A Compliance Compendium. The Ophthalmic ASC. October 2018.
5. Asbell, R.L.: Choosing Sides in Coding. Available at www.RivaLeeAsbell.com . ©2005 Riva Lee Asbell EyeWorld February and April 2005 Reviewed March 2005. Reviewed and Revised July 2008.