MSSP 2027 Final Rule: What Changes for Practices in an ACO

Matteo

Updated November 2026. Written by Matteo Grassi, clinical psychologist and cofounder of HANA Health.

The CY2027 Medicare Shared Savings Program (MSSP) changes are the ACO rules CMS finalized on 4 November 2026 inside the Physician Fee Schedule final rule. For practices in an ACO, four matter most: ACOs can reduce or eliminate Part B cost sharing from 1 April 2027, the APP Plus quality set drops to eight measures, patient notices get simpler, and assignment rules tighten in 2028.

Most of the rule is about benchmarks, which your ACO's finance team will worry about. This piece is about what changes in the exam room and at the front desk.

Key facts

CMS issued the CY2027 Physician Fee Schedule final rule on 4 November 2026, and it takes effect on 1 January 2027. (Federal Register, 2026)
From 1 April 2027, approved ACOs can reduce or eliminate Part B cost sharing for most services, except DMEPOS and prescription drugs. (CMS, 2026)
The APP Plus quality set falls to eight measures in 2027, after CMS removed measures 305 and 493. (CMS, 2026)
The shared savings rate for BASIC track Level E rises from 50% to 60%. ENHANCED stays at 75%. (CMS, 2026)
511 MSSP ACOs serve 12.6 million people with Traditional Medicare in 2026. (CMS, 2026)
In performance year 2024, MSSP ACOs earned $4.1 billion in shared savings and saved Medicare $2.5 billion. (CMS, 2026)

What did the CY2027 final rule change for the Shared Savings Program?

The rule changes how ACOs earn savings, which quality measures count, how patients are told about the ACO, and how patients are assigned. CMS projects the package will add up to 1 million assigned beneficiaries in an average year and raise net federal savings by $5.5 billion over 10 years.

The financial changes sit mostly with the ACO entity:

BASIC Level E sharing rate: up from 50% to 60%, which narrows the gap with the ENHANCED track at 75%.
ENHANCED regional adjustment: the maximum weight for lower spending ACOs drops from 50% to 35%.
Prior savings adjustment: the scaling factor rises from 50% to 75%, which softens the rebasing "ratchet" after a good agreement period.
Benchmark cap: the 5% cap on upward adjustments becomes risk adjusted, so ACOs with sicker patients can get a larger adjustment.
Growth adjustment: a new benchmark bonus for ACOs that recruit clinicians and patients new to value based care.

If your ACO is applying for a 1 January 2027 start, CMS lets it change its final track or level during the Phase 2 request for information window, 12 to 17 November 2026. That's this week, so ask your ACO which track it picked and why.

Can ACOs waive patient copays in 2027?

Yes, with approval. Starting 1 April 2027, an ACO approved by CMS can enter Part B cost sharing support arrangements with its participant practices to reduce or eliminate cost sharing for eligible patients. It covers Original Medicare Part B items and services except DMEPOS and prescription drugs.

This is a big shift from today. Outside a sanctioned arrangement, routinely waiving copays is risky, which we covered in our piece on CCM patient cost sharing and waivers. The new policy gives ACOs a CMS approved path instead.

What practices should know:

The ACO applies, not the practice. CMS approves both the ACO and its participating practices.
CMS says it will collect initial applications in early 2027 so approved ACOs can start in the second quarter of 2027.
The ACO chooses which categories of services and which eligible patients get support, under an implementation plan CMS approves.
CMS is removing the prepaid shared savings option. Current participants keep getting those payments through 31 December 2027.

For care management, this matters. CMS's stated aim is to remove cost barriers to services that help patients' health, and a monthly coinsurance bill is exactly that kind of barrier for some patients. If your ACO covers that cost, the enrollment conversation changes. Ask whether care management codes will be in its plan.

Which quality measures count for MSSP ACOs in 2027?

From performance year 2027, the APP Plus set has eight measures. CMS removed Initiation and Engagement of Substance Use Disorder Treatment (305) and Adult Immunization Status (493).

CAHPS for MIPS (321): patient experience survey.
Hospital wide readmission (479): administrative claims.
Admissions for patients with multiple chronic conditions (484): administrative claims.
Diabetes: glycemic status above 9% (001): reported by the ACO.
Depression screening and follow up plan (134): reported by the ACO.
Controlling High Blood Pressure (236): reported by the ACO.
Breast cancer screening (112): reported by the ACO.
Colorectal cancer screening (113): reported by the ACO.

Measures 001, 134 and 236 reported as Medicare CQMs are scored with flat benchmarks. CMS also kept the MIPS CQM collection type available for 2027 and later, and added a new Medicare eCQM option that reports on assigned patients only.

Two of the eight are claims based measures about hospital use. You don't report them; your patients' admissions do. That's where work between visits shows up. For more on the blood pressure measure, see how practices close blood pressure gaps between visits, and for the wider picture, ACO quality measures for practices.

What changes in the ACO patient notice?

The notice gets simpler from 1 January 2027. Practices no longer have to hand the standardized written notice at the patient's first primary care visit, and the required verbal or written follow up is gone.

Instead, the ACO or its participant practice must give each patient the notice at least once per agreement period, by 30 May unless CMS sets a later date. That moves the job from the check in desk to a planned mailing or portal message. Confirm with your ACO who sends it, so you don't do it twice or not at all.

How does patient assignment change in 2027 and 2028?

Two changes matter to practices:

New primary care codes count for assignment from 2027: Screening, Brief Intervention and Referral to Treatment, vaccine adverse effects management, and advance care planning codes join the primary care service list.
Billing outside the ACO counts less from 2028: primary care services billed by an ACO clinician through a non ACO tax ID will be excluded from the assignment calculation.

If any of your clinicians bill under more than one tax ID, talk to your ACO before 2028. The rule targets billing patterns that shift which patients land in the ACO.

CMS also changed advance investment payments from performance year 2028. Eligible ACOs will get $45 a quarter for each beneficiary who's dually eligible, enrolled in the Part D low income subsidy, or living in a rural county, and $25 a quarter for others.

What this means for your practice

Most of this rule happens to your ACO, but three items land on your schedule:

Cost sharing support: ask your ACO now whether it plans to apply in early 2027, and which services it will cover. Care management, transitional care and annual wellness visits are worth raising.
Quality work between visits: the measure set is smaller, so each measure carries more of the score. Blood pressure, glycemic status, depression follow up and admissions all respond to regular contact, not just visits.
Notices and billing: sort out who sends the beneficiary notice and check any clinician who bills under a second tax ID.

If you run CCM or APCM inside an ACO, the copay change is the one to watch. It could take a monthly bill out of the enrollment conversation.

HANA Health supports practices with patient outreach and care management calls between visits; you can see how on our practice care management page. For the bigger model picture, read our explainer on ACO REACH ending and the LEAD model.

Frequently asked questions

When can MSSP ACOs start waiving Part B copays?

From 1 April 2027 at the earliest. CMS will take initial applications in early 2027, and only approved ACOs and their approved participant practices can reduce or eliminate cost sharing.

Does the ACO cost sharing waiver cover DME or drugs?

No. The policy excludes DMEPOS and prescription drugs. Other Original Medicare Part B items and services can be included in an ACO's approved plan.

Is the prepaid shared savings option still available in 2027?

No new ACOs can join it after the application cycle for the 1 January 2027 start. ACOs already in it receive prepaid payments through 31 December 2027.

How many quality measures does an MSSP ACO report in 2027?

The APP Plus set has eight measures: five reported by the ACO, two from administrative claims, and the CAHPS for MIPS survey. The ACO reports the five clinical measures, not each practice on its own.

Do practices still give the ACO notice at the first visit?

Not from 1 January 2027. The notice must be given at least once per agreement period, by 30 May unless CMS sets a later date, and the follow up communication is no longer required.

Sources

Centers for Medicare and Medicaid Services. CY 2027 Physician Fee Schedule Final Rule (CMS-1848-F): Medicare Shared Savings Program fact sheet. 2026.
Federal Register. Medicare and Medicaid Programs; CY 2027 Payment Policies Under the Physician Fee Schedule (final rule). 2026.
U.S. Department of Health and Human Services. CMS Finalizes CY 2027 Physician Fee Schedule. 2026.
Centers for Medicare and Medicaid Services. 2026 Medicare Accountable Care Organization Initiatives Participation Highlights. 2026.
Centers for Medicare and Medicaid Services. Shared Savings Program Fast Facts, as of 1 January 2026. 2026.

This article is educational and isn't billing, coding, clinical or legal advice. Check current CMS guidance, your ACO's policies and your MAC before you bill. If you want to talk through care management inside your ACO, book a call with Matteo.