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October 21, 2025

Modifier CS: Cost Sharing for COVID-19 Testing and Visits Related to Testing

This post discusses Medicare changes at the START of the PHE.  It is for HISTORICAL REFERENCE ONLY.

  • Effective retroactively to 3/18/20, there is no cost sharing allowed for COVID-19 testing or for the evaluation visits related to the testing
  • Medicare instructs us to use modifier CS on the visits and tests, and to contact your MAC and request to resubmit applicable claims with dates of service on or after 3/18/20 with the CS modifier to receive 100% payment (effective until the end of the public health emergency)

Two laws changed cost-sharing rules

The Families First Coronavirus Response Act (FFCRA) waives cost sharing, both coinsurance and deductible amounts, for Medicare patients receiving COVID-19 testing-related services, as well as testing. The Coronavirus Aid, Relief, and Economic Security Act (the CARES Act) amended the FFCRA to provide a broader range of diagnostic items and services that plans must cover without any cost sharing requirements or prior authorization or other medical management requirements.

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Modifier CS Cost sharing waived for specified Covid-19 testing related services 

Use the modifier for these services:

  • The service results in an order for or administration of a COVID-19 test
  • The service is related to furnishing or administering the test
  • The service is for the evaluation to determine if the patient needs a COVID-19 test

CMS specifically lists these E/M services as included:

  • Office and other outpatient services
  • Hospital observation services
  • ED services
  • Nursing facility services
  • Domiciliary, rest home, or custodial care services
  • Home services
  • Online digital E/M services

And, in these settings:

  • Hospital outpatient departments paid under the OPPS system
  • Medical services paid under the physician fee schedule
  • Critical access hospitals
  • Rural health centers
  • Federally qualified health centers.

CMS states that physicians must notify their MAC and request to re-submit applicable claims for full payment. Institutional claims, including hospitals, CAHs, RHCs and FQHCs must resubmit applicable claims with modifier CS to receive 100% of payment.

You can use modifier CS on both in-person visits and visits via telehealth. If using modifier 95, for telehealth services, I suggest reporting it like this: 99214 -CS -95. Modifier CS affects payment, so use it first. Modifier 95 is informational.

It is not for use when treating Covid, unfortunately.

Does the patient need to test positive to use the modifier?

No.

Services that are covered

First, let me quote from the FAQ document released April 11, 2020, which you can download at the end of this article.

“The Centers for Disease Control and Prevention (CDC) advises that clinicians should use their judgment to determine if a patient has signs and symptoms compatible with COVID-19 and whether the patient should be tested. In addition, the CDC strongly encourages clinicians to test for other causes of respiratory illness.

Therefore, for example, if the individual’s attending provider determines that other tests (e.g., influenza tests, blood tests, etc.) should be performed during a visit (which term here includes in-person visits and telehealth visits) to determine the need of such individual for COVID-19 diagnostic testing, and the visit results in an order for, or administration of, COVID-19 diagnostic testing, the plan or issuer must provide coverage for the related tests under section 6001(a) of the FFCRA.

This coverage must be provided without cost sharing, when medically appropriate for the individual, as determined by the individual’s attending healthcare provider in accordance with accepted standards of current medical practice. This coverage must also be provided without imposing prior authorization or other medical management requirements.”

Evaluating a patient, considering ordering a COVID-19 test

What if the clinician is assessing someone with signs and symptoms that are suspicious for COVID-19, and orders or performs the lab test, the visit and other lab tests need to diagnosis the patient to determine the need for COVID-19 testing must be provided by the insurer without cost sharing. The guidance is not 100% clear on this. You could interpret the quote above to mean yes. The CMS outreach from April 7 said,” Cost-sharing does not apply for COVID-19 testing-related services, which are medical visits that: are furnished between March 18, 2020 and the end of the Public Health Emergency (PHE); that result in an order for or administration of a COVID-19 test; are related to furnishing or administering such a test or to the evaluation of an individual for purposes of determining the need for such a test; and are in any of the following categories of HCPCS evaluation and management codes…” (and listed the codes above)

  • The patient presents with cough and shortness of breath. The physician suspects COVID-10, but orders a rapid flu test to rule out influenza. The influenza test is negative. The physician then orders a COVID-19 test. The visit, the influenza test and the COVID-19 test should all be paid by Medicare and private insurers without cost sharing. At this writing, I suggest appending modifier CS on all of the related services.
  • The rule says that services that “relate to the furnishing or administration” of COVID-19 or that relate “to the evaluation of such individual for purposes of determining the need for diagnostic testing” must be covered.
  • The article also requires no cost sharing related “to the evaluation of such individual for the purposes of determining the need for the individual for the product.” The “product” in this sentence is the testing.
  • If doing the visit via telehealth, I suggest using modifier CS and 95, with modifier CS in the first position, but I am basing this on my interpretation of the two citations, above.

CMS, of course, can’t mandate how to bill private insurance companies. It seems likely to me that most will use the CS modifier, as well, and they must provide retroactive coverage. In the additional resources section below, we have provided a link to the list of services to which modifier CS can be applied, and the MLN Matters article.

Keep in mind, it isn’t for use for treatment of Covid.  It is for the E/M evaluation that determines the need for the test.

Additional Resources

  • FAQ about the FFCRA and CARES Act here.
  • MLN Matters Covid-19 resource
  • CS modifier code list

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Last revised September 22, 2025 - CodingIntel Editor

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