G-codes Explained

Practice managers, software companies react to new Medicare billing regulations

Management Focus

Functional G-code reporting for all therapy services provided to traditional Medicare beneficiaries officially began on Jan. 1, 2013. CMS has allowed for a trial reporting period, meaning that therapists would not be penalized for incorrectly submitting or omitting G-codes until July 1, 2013.

If G-codes are not properly submitted in documentation and billing after this date, therapists will not be paid for their services.

This has caused challenges not only to therapists but also to documentation software and billing companies. In order to remain compliant, individuals must have an understanding of the billing for G-codes, as well as how to properly document them in their notes.

Implementation and Documentation

Upon the patient’s initial evaluation, the therapist will determine a particular functional goal to be represented by a G-code and tracked during the therapy episode. The therapist and patient will choose this functional goal based upon the following criteria – it is the functional goal that’s clinically relevant to a patient’s success, has the potential to yield the greatest functional progress, and is a high priority for the patient’s quality of life.

Therapists will evaluate, document and treat all functional limitations related to the plan of care and patient goals; however, only one functional limitation G-code will be documented and billed for at a particular time. This functional goal must be included in the plan of care.

G-codes are divided into categories established from the International Classification of Functioning, Disability and Health (ICF).The therapist will determine the appropriate category for that functional goal that they have chosen to report on.

Categories of G-codes are divided into sets of three. The top G-code represents the current level of function; the middle is the projected level of function; and last represents the discharge level of function. At all intervals except discharge, the therapist will document and bill the current and projected G-codes. At discharge, the therapist will report the discharge and projected G-codes. At every interval, a projected G-code will be billed and documented.

Every G-code billed and documented will have a severity modifier attached to it. A severity modifier is a two-digit code that begins with the letter C. A severity modifier represents the patient’s percentage of disability. The therapist will determine the percentage of disability based upon the results of multiple measurement tools that have been proven reliable and valid in the literature and the therapist’s professional judgment.

To maintain compliance, the therapist will need to include in their documentation how they determined the percentage limitation. The severity modifiers assigned to the current and discharge G-codes will utilize the objective tests.

The severity modifier assigned to the projected G-code will be based upon the therapist’s prediction of how the patient is expected to progress based upon their professional judgment.

When a patient has reached their projected goal for discharge from the G-code that had been tracked at the initial evaluation and the patient is continuing therapy, that G-code will be discharged and a new functional goal represented by a G-code will now be reported on. The new G-code will be documented in the therapy notes on the same day as the discharge G-codes, but billed on the following visit.The therapist will perform the same objective measures at each reporting interval to determine the percentage of disability, and assign the corresponding severity modifier to the appropriate functional G-codes that they are reporting on. The therapist will report G-codes with their severity modifiers at the following times: when they bill CPT codes 97001, 97002, 97003, and 97004 (PT/OT evaluation and re-evaluation respectively); at a minimum of every 10th visit; and at discharge.

Exceptions to the Rule

With every rule there are exceptions. Multiple G-Codes, up to six, will be submitted when a beneficiary receives therapy services under multiple plans of care from a PT, OT, and/or SLP that work for the same Medicare provider.

Three G-codes for current status, projected status, and discharge status, with their severity modifiers, will be documented and billed if a patient is being seen by a particular therapist for only one visit.

However, if you are billing an L-code for a one-time only therapy visit and the code is submitted without a therapy modifier (GP less than GO, or GN), then you would not include the functional limitation data.

Lastly, if the patient discontinues therapy prior their discharge date, G-codes will not be documented nor billed.

Software and Measurement Tools

CMS endorses several objective measurement tools, such as the Activity Measure-Post Acute Care (AM-PAC), FOTO Patient Inquiry, OPTIMAL, and NOMS (for speech-language pathologists). However, you can use any tool that’s been proven reliable and valid in the literature to help determine the percentage of limitation/severity modifier.

In certain cases, an individual’s functional limitation may not be reflected by the measurement tool; this is why they advocate the use of several objective tools to determine percentage of limitation/severity modifier.


  1. Clarification of the IFC Categories. (2012). Retrieved Feb. 21, 2013, from www.apta.org/Payment/Medicare/CodingBilling/FunctionalLimitation/
  2. Outpatient Therapy Functional Reporting Non-Compliance Alerts. (2013). Retrieved April 5, 2013, from www.cms.gov/Regulations-and-Guidance/Guidance/Transmittals/Downloads/R1196OTN.pdf
  3. Implementing the Claims-Based Data Collection Requirement for Outpatient Therapy Services. (2012). Retrieved March 6, 2013, from www.cms.gov/Outreach-and-Education/Medicare-Learning-Network MLN/MLNMattersArticles/Downloads/MM8005.pdf
  4. Implementing the Claims-Based Data Collection Requirement for Outpatient Therapy Services. (2012). Retrieved April 26, 2013, from www.cms.gov/Regulations-and-Guidance/Guidance/Transmittals/Downloads/R165BP.pdf

Notes on Billing

  1. G-codes will always be reported with a severity modifier. Severity modifiers are represented by the codes CH-CN and reflect a percentage of disability that a patient has in a particular functional activity that is represented by the G-code.
  2. G-codes will billed with their appropriate therapy modifiers (GP for physical therapy, GO for occupational therapy).
  3. The acceptable charge for G-codes are $0.00 or $0.01.
  4. There are no units assigned to the G-codes.
  5. G-codes are reported in Box 24D for the HCFA and Box 44 for the UB-40.
  6. In the simplest cases, on the HCFA or UB-40 claim form, 2 G-codes with their severity modifiers will be reported at the following times: the initial evaluation, every 10th visit, and discharge. There are exceptions to this case.
  7. The middle G-code that represents the projected level of function will always be reported with the current level of function at the initial evaluation and every 10th visit, and with the discharge G-code at discharge.
  8. If a patient reaches their initial functional G-code goal and will be continuing with therapy, the current and discharge goal will be billed that day. The new G-code, current and projected, with the appropriate severity modifier, will be billed at the following session even if a different provider is treating the patient on that day.
  9. Three G-codes are submitted for current status, projected status, and discharge status, along with their corresponding severity modifiers when a patient is being seen only one time by a particular therapist.
  10. Multiple G-codes, up to six, will be submitted when a beneficiary receives therapy services under multiple plans of care from a PT, OT and/or SLP who work for the same Medicare provider.

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