Why Are ASC Payment Rates Lower Than Hospital Rates?

Medicare pays ASCs and hospital outpatient departments from two different systems, and ASC payment rates sit below the hospital rate for the same procedure. CMS publishes both quarterly, so the gap is checkable per CPT code, and a missed procedure costs an ASC proportionally more.

National unadjusted rates, July 2026 quarterly update. ASC figures from CMS Addendum AA , hospital figures from CMS Addendum B . Your own rates differ by locality once the wage index is applied.

What are ASC payment rates, and how do they differ from hospital rates?

An ASC payment rate is what Medicare pays a certified ambulatory surgical center for a covered surgical procedure, published per HCPCS code in Addendum AA. The hospital outpatient rate is what Medicare pays a hospital outpatient department for the same code under the Outpatient Prospective Payment System, published per code in Addendum B with its APC assignment.

Two separate systems, two separate sets of published rates, updated on the same quarterly clock. Both are national unadjusted figures before the wage index and any other locality adjustment.

The comparison is exact because the code is the same on both sides. Take 49650, a laparoscopic inguinal hernia repair. In an ASC the facility payment is $3,030.97. In a hospital outpatient department the same code maps to APC 5361 and pays $6,176.47. Nothing about the operation changed. The building did.

Why does the gap matter more to an ASC than to a hospital?

A hospital outpatient department absorbs a missed charge into a much larger cost base. An ASC does not. The facility payment is the revenue for the case, and it starts from a lower number.

Work the same error through both settings. A documented procedure that never reaches the claim costs a hospital the OPPS rate. It costs an ASC the ASC rate, which is the smaller figure, but the ASC has less margin behind it to absorb the loss. The proportional damage is larger even though the absolute dollar amount is smaller.

That asymmetry is why capture discipline is a different conversation in an ASC. A hospital can carry a coding backlog and a few uncaptured lines as a rounding error inside a service line. An ASC is closer to a single-product business, and every case it codes is a larger share of the month.

None of this is an argument that ASCs are underpaid. That is a policy debate with its own literature. It is an operational observation: the lower the base rate, the more each captured or missed procedure matters to the facility running it.

What did CMS finalize for CY2026?

Both systems got the same update. CMS finalized "an update to the OPPS payment rates for hospitals that meet applicable quality reporting requirements by 2.6%," based on "the hospital market basket percentage increase of 3.3%, reduced by a 0.7 percentage point productivity adjustment." For ASCs, CMS "finalized an update factor to the ASC rates of 2.6%," from the same market basket figure and the same productivity adjustment.

That matters for how you read the gap. The two systems did not drift apart this year. They moved in step, from the same inputs, and the difference between them stayed where it was.

The reason ASCs receive the hospital market basket at all is an interim policy. CMS first applied it "for an interim period of five years (CY 2019 through CY 2023) while CMS determined the impact of the higher update factor on the migration of services from the hospital outpatient setting to the ASC setting." For CY2026 CMS extended that arrangement "one additional year, through CY 2026, while CMS continues to study the migration of outpatient surgical procedures."

So the update mechanism an ASC is paid under is reviewed annually and is not permanent. That is worth knowing before building a multi-year model on it.

What do people get wrong about this comparison?

The gap is not an annual update problem. Both sides took 2.6% for CY2026. Anyone explaining the difference by pointing at this year’s update is describing the wrong mechanism. The difference sits in the base rates, not in the yearly change.

The ratio is not constant across procedures. Most of the table sits near half the hospital rate. Total knee replacement does not: $9,393.16 against $13,116.76. Its ASC payment indicator is J8 rather than A2, which is CMS’s marker for a different payment treatment. Averaging the two settings into a single percentage and applying it across a case mix will misprice exactly the cases that carry the most revenue.

A published rate is not your rate. Everything above is national and unadjusted. The wage index moves it by locality before anything is paid, and commercial contracts follow their own schedules entirely.

What should an ASC do with these numbers?

Price your own top cases rather than a national average. Pull your twenty highest-volume codes, put the ASC rate and the hospital rate side by side, and apply your own case mix. The arithmetic is yours to do and it is more useful than any published ratio.

Check the payment indicator, not just the rate. A2 and J8 are not the same treatment, and the indicator tells you which procedures behave differently before the dollar figure does.

Reload the addenda every quarter. Both files update quarterly. A rate table built in January drifts, and the drift shows up as an unexplained variance in the spring.

Then look at capture. Given a lower base rate, the cost of a documented procedure that never reaches the claim is proportionally larger here than anywhere else in outpatient care. A coding audit that compares operative notes against submitted claims tells you whether that is happening, and it is the cheapest thing on this list to run.

Where coding accuracy fits

The operative note is the whole record for an ASC case, and everything billable has to be read out of it. Complete charts flow through AutoPilot for fully autonomous coding. Charts where the documentation is thin or contradictory stay in CoPilot, where certified coders review and finalize the output.

Every code ships with its documentation passage and the compliance rule behind it, which is what makes a capture question answerable after the fact rather than arguable. See ASC medical coding for how that runs against operative notes, and computer-assisted coding software for how it differs from a suggestion list.

What has not changed

The covered procedures list still governs what an ASC may bill at all. A rate in Addendum AA tells you what a procedure pays in an ASC, not whether this patient was appropriate for the setting.

Coding rules did not move because payment did. The documentation still has to support every code, and site of service changes the rate rather than the standard.

And commercial payers set their own terms. A contract priced against Medicare will track these files; one priced on its own schedule will not. See security and compliance for how the coding record behind either is retained.

See what this looks like on your own charts

Book a Demo and we will run an accuracy check against a sample of your own ASC charts, so you can see which procedures the first pass captures from the operative note and which ones your current process is leaving off.

Related: ASC medical coding · Coding audit services · RCM medical coding .

Sources

1. CMS, Calendar Year 2026 Hospital Outpatient Prospective Payment System (OPPS) and Ambulatory Surgical Center Final Rule (CMS-1834-FC), fact sheet. cms.gov
2. CMS, ASC Payment Rates Addenda, July 2026, Addendum AA. cms.gov
3. CMS, Hospital Outpatient Regulations and Notices, July 2026 Addendum B. cms.gov