How pharmacies ask CMS to review a NADAC rate

In the week ending June 3, 2026, CMS cut its benchmark for what retail pharmacies pay for a generic dapagliflozin 10 mg tablet, a diabetes drug, from $11.37 to 20 cents. For 30 tablets, that took the published acquisition cost from $341.03 to $6.15. The reason recorded in CMS's NADAC comparison file¹ was "Help Desk," which CMS's field definitions² describe as a rate "updated as a result of an inquiry to the help desk."

Changes like that are rare. In all of 2025 the comparison file logged 342,674 rate changes at the level of individual drug codes. Of those, 341,139 came from the monthly survey, 1,454 from brand list-price adjustments, 11 from regrouping, and 70 from help desk reviews. Those 70 covered just 14 drug descriptions (a name, strength and form), by GxRadar's count.

The rate in question is NADAC, the National Average Drug Acquisition Cost, and it matters well beyond one file. By GxRadar's count of CMS's state reimbursement summary¹¹, 47 of 53 Medicaid programs use it in their formula for paying pharmacies, as our explainer on how state Medicaid programs pay for generics describes. When a pharmacy's invoice cost for a generic climbs past the published rate, the help desk is the route CMS offers for changing it between monthly surveys. This piece explains how a review starts, what the help desk checks, what has to happen for a rate to move, and how often it does.

Weekly files, monthly surveys

CMS posts a full NADAC file every week. The monthly file, which carries the latest survey results, is produced "on the first Monday on or after the 15th of each month," according to the agency's NADAC page⁴, and every other file that month is a weekly posting. The survey runs about two months behind. In the example in CMS's December 2024 methodology³, invoices for November purchases are collected and processed in December and published in January.

Between monthly files, the methodology allows two kinds of change. Brand rates move with published list prices, so a 5 percent increase in a brand's wholesale acquisition cost raises its NADAC 5 percent. Generic rates have no automatic list-price adjustment. The methodology's route for a mid-month generic price change is the help desk, which revises a rate when its research "substantiates that a change in price for a generic drug has occurred." Since December 2024, CMS has also calculated each monthly generic rate as a three-month moving average of survey results, which slows how fast new invoice prices reach the file. Our explainer on how NADAC is calculated covers the survey math, and the 2024 NADAC swings covers why CMS made the change.

How a review starts

The NADAC help desk is run by CMS's survey contractor and staffed by "certified pharmacy technicians, trained analysts, and pharmacists," the methodology says. CMS lists its contact points on the Retail Price Survey page⁵: a toll-free line, (855) 457-5264, a fax line, (844) 860-0236, and an email address, along with a one-page request for review form⁶. The form, dated April 2020, asks for one drug per submission and collects:

• the pharmacy's name, NPI, type and location;
• the drug name, strength and 11-digit NDC;
• the cost per package, package size and purchase date;
• the claim at issue, including the payer, dispense date, quantity, dispensing fee and total payment;
• whether the acquisition cost rose recently and what it was before, whether there is an availability problem, and whether other NDCs of the drug can be bought, with their costs.

The form says that requests "submitted without purchase record or invoice supporting your acquisition cost will not be considered for review," and asks pharmacies not to include patient health information. A single request is enough. "Each individual inquiry is sufficient to initiate a review," CMS wrote in its NADAC questions and responses⁸, and it answered "Yes. Anyone can contact the Help Desk" when asked whether manufacturers may call too. The help desk does not take up questions about a particular state's claim payments; CMS sends those to the state Medicaid agency.

What the help desk checks

Reviews are "investigated and evaluated based upon invoice data collected from the pharmacy initiating the review, additional pharmacies contacted by the Help Desk, and other market factors, such as compendia pricing changes and drug shortages," the methodology says. CMS's 2017 overview for states⁷ added other considerations, including the number of cost observations behind the current rate, recent monthly averages, other states' acquisition cost rates, labeler changes and "changes in the number of labelers producing the drug."

A higher invoice alone does not move the rate. NADAC is an average, so "some pharmacies will purchase covered outpatient drugs on invoice below the NADAC rate and some pharmacies will purchase covered outpatient drugs on invoice above the NADAC rate," the methodology notes. If the inquiring pharmacy's cost falls within the range of invoice costs already used and newer invoices show no change, the rate stays put. Pharmacies are told the outcome and can also watch the next weekly file.

The current methodology sets no fixed percentage that triggers a change. An older rule did exist for survey results: CMS's 2017 overview described an explanation code 2, used when "the average acquisition cost of the most recent survey was within ± 2% of the current NADAC," so the old rate was carried forward. The December 2024 methodology lists code 2 as "not currently used." CMS's separate NADAC data field definitions⁹, revised in January 2021 and still linked from the Retail Price Survey page, describe the code the old way, so a reader may find both versions.

Timing matters for pharmacies. Help desk changes take effect on the date of the weekly file that publishes them and "will not be backdated," the 2017 overview says. States that want to pay the new rate on earlier claims must build that into their own claims systems.

How often rates change this way

GxRadar downloaded every help desk row in the comparison file, which begins in December 2013. The table counts each drug description changed in a given week once, however many drug codes it covered.

Over the whole period, including nine changes in December 2013, 1,080 drug descriptions were changed this way, and 93.5 percent of the changes were increases. That fits what the help desk reported in 2017. It received about 1,500 calls from April to June 2017, the overview said; 5 percent of rate inquiries led to an adjustment, and "all calls received were requesting increased drug ingredient reimbursement." The same slides noted that about 60 percent of the pharmacies submitting inquiries had been included in a monthly survey during 2016, "but only 35% responded to the survey request."

The recent cases run in both directions. Four from 2025 and 2026, shown per 30 tablets because these drugs are not in GxRadar's fill-size file:

The file does not say who made these inquiries or what the reviewers found. The same mechanism produced one of the biggest moves in GxRadar's price basket, the 131 percent jump in tamsulosin's rate in November 2014, told in our tamsulosin and finasteride price history. All of these are acquisition costs from the NADAC files¹⁰, not prices at the counter.

The survey behind the rate, and the bills to change it

NADAC exists because the 2016 Covered Outpatient Drugs rule¹² required states to pay actual acquisition cost, and NADAC is one way to meet it. Answering the survey is voluntary. "Since participation in the NADAC survey is voluntary, each sampled pharmacy has the option to submit a response," CMS wrote in its questions document. CMS's NADAC page attributes the rate volatility of 2024 to "fluctuations in survey participation." Our piece on how the survey picks pharmacies covers the sample.

Bills to make responses mandatory keep returning. The Protecting Pharmacies in Medicaid Act¹³, S. 927, introduced March 11, 2025, and referred to the Senate Finance Committee, would require pharmacies paid by Medicaid to respond, enforce that with civil money penalties, and require CMS to publish the monthly response rate, "including a list of pharmacies not in compliance." It would also extend the survey, on a later schedule, to "applicable non-retail pharmacies," a category that includes mail-order and specialty pharmacies. The Consolidated Appropriations Act, 2026¹⁴, signed Feb. 3, 2026, carried federal pharmacy benefit manager provisions, covered in our piece on the 2026 PBM law, but GxRadar's review of its text found no change to the NADAC survey provisions in section 1927(f) of the Social Security Act.

What to watch

The next monthly NADAC file is due Monday, Nov. 16, 2026. CMS has said it plans to seek stakeholder input on a permanent replacement for the three-month moving average. Until then, the route for a pharmacy whose invoices run above the published rate is the one on CMS's form, one drug per request with the invoice attached.