The CY 2027 OPPS/ASC Proposed Rule is a negotiation leverage Map, not just a payment update

On July 2 -- in the shadow of the 250th Independence Day celebration -- CMS released the 2027 Hospital Outpatient Prospective Payment System (OPPS) and Ambulatory Surgical Center (ASC) proposed rule. Comments are open through August 31 with a final rule typically posted in November.

Initial news coverage has focused, as it usually does, on the headline rate update. That's probably the least interesting part of this rule.

For anyone building rate benchmarks, evaluating counterproposals, modeling site-of-service economics, or buried in revenue-budget models for an October fiscal year start, three provisions matter more than the top-line percentage -- because they change where CMS wants volume to flow and where negotiation leverage sits in every outpatient-focused contract for the next 18-24 months.

The headline number, briefly

I'd be remiss to not cover the headline figure -- a 2.4% update to both OPPS and ASC payment rates. This reflects a 3.2% market basket increase -- which falls short of the 4.2% CPI-U increase over the last twelve months -- less a 0.8% productivity adjustment. This compares to a 2.6% net increase for 2026 which featured a 3.3% market basket increase against a 0.7% productivity adjustment.

Overall, CMS projects facilities will see a 1.9% net increase on average once wage index and APC reweighting items are layered in. That average, however, conceals wide variation by facility type, region, and -- as covered below -- 340B exposure.

The biggest message:

Don't benchmark off the topline number.

Site-of-service map keeps shifting towards freestanding sites (like ASCs)

This is year two of a three-year phaseout of the Inpatient Only (IPO) list. CMS is proposing to remove up to 638 more procedures on top of the 285 removed in 2026's final rule. In lockstep, the ASC Covered Procedure List (CPL) is slated to grow by 618 procedures - following 560 additions for CY26.

The two moves are related: as CMS decides a procedure no longer needs a inpatient stay, it becomes eligible for both the OPPS and ASC fee schedule.

For health systems with ASCs, this becomes an offensive opportunity: a growing set of procedures CMS is actively guiding towards a lower-cost setting with reimbursement rules that are increasingly favorable. For payers and self-insured employers, it's a benchmarking gap: any rate model that doesn't yet have freestanding-specific pricing for codes that were previously inpatient-only or hospital-only becomes obsolete. For anyone running counterproposal frameworks against these scenarios, the volume assumptions imbedded in an inpatient vs. outpatient setting no longer hold.

Site-neutral payment reaches imaging

In 2019, CMS adopted a method to cap what Medicare pays for clinic visits at off-campus provider-based departments, bringing those payments down to something closer - but not quite equal to - physician office rates. That 2026 policy expanded to drug administration services in CY2026 final rule that was published in November 2025. For CY2027, CMS proposes adding imaging-without-contrast - which covers the majority of outpatient MRIs - to the list, paid at the Physician Fee Schedule-equivalent rate rather than the OPPS rate. Rural Sole Community Hospitals are proposed exempt, consistent with prior changes.

CMS estimates this cuts Part B spending by a little over $250 million in the first year alongside another $70 million in reduced beneficiary cost-sharing.

The pattern is now three years running: clinic visits, drug administration, and now imaging. Any organization with meaningful off-campus imaging volume should be modeling the PFS-equivalent rate now rather than waiting for the November final rule that will be released after the current budget cycle wraps up. And more importantly:

Assume the site-neutral list keeps growing in future rulemaking cycles.

340B takes multiple hits

CMS recently ran a hospital-based drug acquisition survey covering roughly 1,300 hospitals (with a 41.4% response rate). The survey found significant gaps between acquisition costs for 340B drugs and non-340B drugs -- in some cases, beneficiary cost-sharing exceeded what the hospital actually paid for the drug!

Based on that data, CMS is proposing to cut the 340B drug payment rate from ASP + 6% to ASP - 33.4%, projecting to save nearly $4.5 billion in Medicare drug spending and $1.2 billion in beneficiary cost sharing for a total of $5.7 billion. For all the concern about site-neutral payments, the potential here dwarfs what site-neutral payments may bring with total cost-savings estimates approaching $6 billion in the first year. These cuts, however, must be budget neutral which means non-drug service rates will have a resulting rise.

Separately, CMS is accelerating the 340B clawback - the mechanism for recovering billions in excess non-drug payments hospitals received in 2018-2022 under the invalidated 340B policy. That offset was set to 0.5% annually starting in 2026 spread over 16 years. CMS now proposes raising it to 3% starting in 2027, completing the total clawback by 2029 instead.

Most Interesting -- and worth watching: the price transparency RFI

CMS has finally included a long-awaited Request for Information (RFI) on strengthening hospital price transparency machine-readable file (MRF) requirements -- specifically seeking comment on standardizing how contract mechanisms like outlier payments, stop-loss provisions, rate tiering, carve-outs, and other unique contractual issues are reported, along with changes to the consumer-friendly price-estimator "deemed compliance" policy and shoppable services list.

This isn't a payment change but a policy change. It's a signal CMS wants MRF data to get more standardized and more comparable across hospitals. This is direcly relevant to anyone trying to use MRF data for rate benchmarking. We'll track this through the comment cycle even though the final rule is still months away.

Other provisions of note

CMS also proposes: a revised Overall Hospital Quality Star Rating methodology that emphasizes the Safety of Care measure group; a cost-of-living adjustment for the nonlabor share of OPPS payments in Alaska and Hawaii (an estimated $55 million benefit to those states); removal of the "Appropriate Follow-Up Interval for Normal Colonoscopy" measure from both quality reporting programs; prior authorization expansion to eight additional botulinum toxin injection codes; and a proposal letting hospital Accrediting Organizations assess EMTALA administrative compliance (signage, ED logs, transfer records) as part of routine surveys, while CMS/OIG retain enforcement over substantive patient care violations.

The takeaway

None of these provisions are final. Comments close August 31, and the numbers can move before the November final rule. But the direction is clear enough to act on now: more volume eligible for ASC and outpatient settings, tighter site-neutral payment for imaging, and a 340B environment where the specifics of a facility's drug mix and enrollment history matter more than ever to its net position. Rate benchmarks and counterproposal frameworks built on last year's assumptions about site-of-service economics or 340B payment levels need to be revisited before they're used in a live negotiation.