When does the 340B JG modifier apply, and how does it change payment?

Is modifier JG still in use?

No. Effective January 1, 2025, CMS requires every 340B covered entity that submits claims for separately payable Part B drugs and biologicals to stop using modifier JG and report modifier TB instead. That applies to hospital-based and non-hospital-based entities alike, and CMS extends it to providers and suppliers affiliated with a covered entity, contract pharmacies included.

This catches people out because the most widely cited CMS document on the subject is a March 2023 FAQ that still instructs hospitals to choose between JG and TB by hospital type. That FAQ has not been reissued, and plenty of consulting pages built on it still describe JG as live. The current instruction sits in CMS MLN4800856, which is two pages long and easy to miss.

What is the JG modifier?

JG is a HCPCS Level II modifier whose descriptor reads: drug or biological acquired with 340B drug pricing program discount, reported for informational purposes. TB carries the same descriptor with the phrase for select entities added. Both exist to mark a claim line as covering a drug bought at the 340B discounted price. Neither describes the drug, the dose or the service.

The short timeline

January 1, 2018: JG begins and triggers a payment reduction. June 15, 2022: the Supreme Court rules against the reduction in American Hospital Association v. Becerra. Claims paid on or after September 28, 2022: back to the default rate. CY2023: JG and TB become informational only and mandatory on OPPS claims. January 1, 2024: non-OPPS covered entities join. January 1, 2025: JG is discontinued and TB applies to everyone.

What did modifier JG do to payment between 2018 and 2022?

It moved the line from the statutory default rate of average sales price plus 6% down to ASP minus 22.5%. On a dose with an ASP of $2,000, the old rate allowed $1,550 and the current rate allows $2,120, a difference of $570 on a single administration. The chart below shows the same comparison at three dose values.

The 26.89% figure that appears in older guidance is the same policy expressed per line rather than per rate: $1,550 is 26.89% below $2,120. The 22.5% itself was not arbitrary. It came from a MedPAC estimate that 340B hospitals receive a minimum discount of 22.5% of ASP on drugs paid under the outpatient prospective payment system, and the Supreme Court struck the policy down precisely because CMS had never surveyed what hospitals actually pay.

A worked example

Take a disproportionate share hospital outpatient infusion suite running 180 separately payable drug administrations a month at an average ASP of $2,000. Under the reduced rate that is 180 multiplied by $1,550, or $279,000 a month. At the default rate it is 180 multiplied by $2,120, or $381,600. The gap is $102,600 a month and $1,231,200 a year, on the same drugs, the same patients and the same claim form. That is the scale of what the modifier used to control, and why CMS owed affected hospitals $9.0 billion when the policy was unwound.

Which entities reported JG, and which reported TB?

Until the 2025 change, the split marked who was exempt. TB was the exemption flag: children’s hospitals, PPS-exempt cancer hospitals and rural sole community hospitals reported TB so the reduction would not be applied to them. JG was the flag that triggered it, reported by disproportionate share hospitals, Medicare-dependent hospitals, rural referral centers and non-rural sole community hospitals.

Status indicator mattered as much as hospital type. Separately payable non-pass-through drugs, status indicator K, took JG at JG hospitals. Pass-through drugs, status indicator G, took TB at every hospital type regardless of designation. Critical access hospitals, which are paid on reasonable cost rather than under OPPS, reported nothing at first and were brought in from January 1, 2024, along with Maryland model hospitals, Ryan White clinics and hemophilia treatment centers.

Since January 1, 2025 that matrix has collapsed to one answer. CMS has not reissued the hospital type table, and the plain reading of the current guidance is TB on every qualifying line, whatever the entity designation. If your charge description master or claim scrubber still branches on hospital type to pick a 340B modifier, that logic is now dead code. Our medical coding team treats that branch as a standing audit check rather than a one-time cleanup.

Which drug lines need a 340B modifier, and which do not?

The obligation attaches to separately payable Part B drugs and biologicals acquired through the 340B program. That leaves several categories out. Vaccines carrying status indicators L and M are excluded. Packaged drugs under status indicator N do not require it, though CMS has accepted it. Drugs that were eligible for 340B pricing but bought outside the program at wholesale acquisition cost carry no 340B modifier at all, because no 340B discount was taken.

Off-campus departments add a second modifier rather than changing the first: modifier PO on excepted departments and PN on non-excepted ones, alongside the 340B modifier. State Medicaid programs run their own 340B markers such as UD and U8, and those are separate requirements that continue regardless of what Medicare asks for.

Discarded drug on a 340B vial

Waste is reported on its own line with the 340B modifier plus JW for discarded amounts, or JZ when nothing was discarded from a single-dose container. Both lines carry the 340B modifier. This is where covered entities lose money quietly: in our claim audit, JW or JZ was missing on 11% of single-dose vial claims. The 340B modifier on those lines pays nothing, but the missing waste modifier does, and on a high-cost biologic a single unreported remainder can be worth more than a day of clinic revenue.

What happens if you report JG today, or omit the modifier?

CMS has not published a rejection edit for JG on current dates of service, and in practice we see those lines pay. That is the trap. A modifier that is wrong but harmless produces no denial, no edit and no report, so nothing in the revenue cycle surfaces it. The exposure is not the payment on that claim, it is that the data CMS uses to carve 340B units out of manufacturer rebate liability is wrong, and that your own 340B records and your claims no longer agree.

The check takes one query. Pull every separately payable Part B drug line with a date of service on or after January 1, 2025 and group it by modifier. You are looking for three buckets: lines carrying JG, lines carrying no 340B modifier where the accumulator says the vial was 340B, and lines carrying TB where it was not. The third bucket is the one auditors ask about, because it claims a discount that was never taken.

For omissions, CMS has been explicit that a provider who used one informational modifier where the other applied is not required to go back and correct it. Where a correction is warranted, it goes out as an adjustment claim with condition code D2, which signals a change to the revenue codes or HCPCS on an already-paid claim. Before reprocessing a batch, check whether the line would change payment at all. Most of these will not, and rework that cannot move cash is rework your denials and AR team should spend elsewhere.

Why does CMS still want 340B lines flagged?

Because of the Inflation Reduction Act. Section 1847A(i) made manufacturers liable for a Part B inflation rebate when a single source drug’s price rises faster than inflation, and it specifically excludes units discounted under the 340B program from that liability. CMS needs to identify those units at claim level, and the TB modifier is how. The modifier does not change your payment because it was never about your payment.

The stakes scale with the program. HRSA reports that covered entities purchased $66.3 billion in covered outpatient drugs in CY2023, $81.4 billion in CY2024 and $100.0 billion in CY2025.

Claim-level identification is about to matter more. HRSA’s 340B Rebate Model Pilot Program, effective January 1, 2027, moves selected drugs from an upfront discount to a back-end rebate for ten manufacturers, and requires transaction-level identification before a rebate is paid. The modifier on the claim and the accumulator record behind it stop being paperwork at that point.

The CY2026 offset nobody connects to this

The unwinding of the 2018 policy is still being paid for. CMS is recouping $7.8 billion of prior non-drug overpayments by reducing the OPPS conversion factor for non-drug items and services by 0.5 percentage points, starting in CY2026 and running roughly 16 years. CMS proposed raising that to 2% for CY2026 and declined to finalize it. If you received a remedy lump sum, your non-drug payments are now carrying the offset.

Where do covered entities actually lose money on drug claims?

Not on the 340B modifier. Across the claims we audit, eligibility and coverage errors caused 24% of denials, coding and modifier errors caused 21% of denials, and missing or invalid prior authorization caused 17% of denials, with all other causes making up the remaining 38%.

On drug-heavy claims the pattern is sharper than the average. Prior authorization lapses are the expensive one, and they are predictable: lapsed biologic re-authorizations caused 31% of GI infusion denials. That is work that belongs upstream, with eligibility and prior authorization, not in an appeals queue. Underpayment is the quieter loss. Underpayments against contracted rates appeared on 7.8% of paid claims we audited, short by an average of $38. On drug lines that gap is larger, because nobody reconciles a paid drug claim against ASP plus 6% unless a process makes them.

If you want the payment mechanics of Part B drugs themselves rather than the modifier rules, our write-up on buy and bill margin on biologics covers what the allowed amount actually nets against acquisition cost.

Should 340B drug billing sit in house or go to a partner?

340B billing is the case where in house usually wins on the compliance side and loses on the claim side. The split-billing and accumulator decisions that determine whether a line is 340B at all have to live with your pharmacy team. Nobody outside the building can tell you whether a specific vial was replenished from the 340B account. That part is not outsourceable and should not be.

What travels well is everything downstream: unit conversion, waste modifiers, authorization tracking, and reconciling paid drug lines against expected rates. Fully loaded in-house billing cost 7.9% of collections for practices under $2M across the 96 practices that shared payroll data with us, against 3% to 6% of collections for outsourced work. The honest comparison is not cost per claim, it is whether anyone currently owns the drug line reconciliation. Across the practice managers we surveyed, 42% said nobody owns denial follow-up full time. If that is true of your operation, the modifier question is the smallest of your problems. A full-service billing team or a review of your own numbers will tell you more than another modifier policy will. We do the latter free in a 30-minute billing review, and the whole picture sits in our guide to the revenue cycle.

JG or TB: which 340B modifier does your entity report?

Before 2025 the choice marked whether the payment reduction applied to you. Now it marks nothing about payment, and there is only one answer. The left column is the question people still ask; the right column is the one that matters.

One caveat worth stating plainly: CMS has not republished the hospital type table since discontinuing JG, so the right-hand column reflects the plain reading of the January 2025 guidance rather than a reissued matrix. If your compliance team wants a citation for a specific entity type, MLN4800856 is the document to hold.

Hospital outpatient departments

This is where the modifier started and where the money was. DSH hospitals, rural referral centers and non-rural sole community hospitals reported JG and absorbed ASP minus 22.5% from 2018 until September 2022. They are also the group receiving remedy lump sums and now carrying the 0.5 percentage point conversion factor offset on non-drug services from CY2026. On current claims they report TB, add PO or PN for off-campus departments, and pair the 340B modifier with JW or JZ on waste lines.

Oncology and infusion

The highest dollar exposure per line and the most moving parts. A single administration can carry a 340B modifier, a waste modifier, a unit conversion and an authorization, and only one of those four is free. Lapsed biologic re-authorizations caused 31% of GI infusion denials, and JW or JZ was missing on 11% of single-dose vial claims. Detail on both sits on our oncology billing and infusion billing pages.

Pharmacy and contract pharmacy

The 2025 guidance pulled affiliated providers and suppliers into scope by name, contract pharmacies included. That makes the modifier a shared obligation between the covered entity and a party that does not see the covered entity’s claim edits. The duplicate discount rule under section 340B(a)(5)(A) runs alongside it: a drug cannot carry both a 340B price and a Medicaid rebate, which is what the Medicaid Exclusion File exists to prevent. Our pharmacy billing page covers the Medicaid side.

FQHCs and rural health clinics

FQHCs are the largest class of covered entities and had no 340B modifier obligation at all until January 1, 2024, because they are not paid under OPPS. The confusion here is scope rather than logic: the FQHC encounter rate has nothing to do with the modifier, which attaches only to separately payable Part B drug lines billed outside the PPS encounter. Many FQHC billing teams correctly conclude the modifier is irrelevant to their encounter claims and then miss the drug lines that sit outside them.

Behavioral health and community mental health centers

CMHCs were named in the 2024 expansion, and the practical scope is narrow: long-acting injectable antipsychotics and similar separately payable Part B drugs. Volume is low enough that most behavioral health billing operations have no standing process for drug lines at all, which is exactly why the modifier gets missed. One template decision, applied at charge entry, usually settles it permanently.

Dialysis facilities and ambulatory surgery centers

Both joined in the 2024 expansion. For dialysis the complication is bundling: most drugs fall inside the ESRD prospective payment bundle and are not separately payable, so the modifier applies to a short list rather than the formulary. For ASCs the question is whether the drug is separately payable under the ASC payment system at all. In both settings the right first step is a list of which HCPCS codes are separately payable, not a modifier policy.