G2211 becomes B1 and B2: the 2027 E/M complexity modifiers

This page summarizes CMS's fact sheets on the CY 2027 Physician Fee Schedule final rule (CMS-1848-F). It is not billing or legal advice. Medicare Advantage plans set their own rules. Have your coder or compliance counsel confirm anything a claim depends on against the rule text in the Federal Register.

What changes on 1 January 2027

G2211 is the office/outpatient E/M visit complexity add-on: a separate code with a flat payment, billed alongside the E/M visit. CMS finalized it in the CY 2021 rule, and statute delayed it until CY 2025.

For 2027, CMS finalized two changes, both as proposed:

1. G2211 becomes a modifier. It is appended to the E/M base code instead of billed as its own line. CMS named it B1 (placeholder MOD1 in the proposed rule).
2. A second, larger modifier for ACO practitioners. B2 (placeholder MOD2) recognizes what CMS calls the "additional resource costs incurred by practitioners in Accountable Care Organizations (ACOs) when providing longitudinal care, such as maintaining total cost of care accountability and reporting quality measures."

Because both are percentages, the add-on now scales with the visit level. A 99215 earns more in add-on dollars than a 99212.

B1 and B2 side by side

Source: CMS, CY 2027 PFS final rule fact sheet, section "E/M Visit Complexity Add-On (HCPCS code G2211)".

Three things about B2 that matter for an ACO

It isn't limited to assigned patients. Under the Shared Savings Program, a participating practitioner can bill B2 for every Medicare beneficiary they see, not only the ones assigned to the ACO. The same holds under LEAD for non-aligned beneficiaries.

It shows up in the ACO's spending. Claims with B2 count in assignment calculations, the historical benchmark and performance-year expenditures. The extra payment to the practice is also spend the ACO is measured against.

It's tied to what the ACO is already accountable for. CMS names total-cost-of-care accountability and quality reporting as the resource costs B2 recognizes. That same rule sets the 2027 quality measure set for Shared Savings Program ACOs: see MSSP quality measures for 2027.

What this means for an independent practice

From 2027, a practice's E/M add-on depends on whether it's in an ACO: 16% outside one, 32% inside a Shared Savings Program or LEAD ACO. That difference applies across the practice's Medicare E/M visits, since B2 isn't limited to assigned patients.

The rest of the decision is the rest of the ACO: its quality reporting, its care-management expectations, and its shared-savings terms. The same rule raises the BASIC track Level E sharing rate from 50% to 60% and lets ACOs apply to reduce or eliminate Part B cost sharing from 1 April 2027.

The conversion factor behind the percentage

B1 and B2 are percentages of the E/M payment, so they move with the conversion factor. For 2027, as published by CMS on 4 November 2026:

CMS attributes most of the drop to the end of the one-year 2.50% increase for CY 2026 under Public Law 119-21.

Other E/M changes in the same rule

• Same-day E/M with a 0-day global procedure. When a separately identifiable office/outpatient E/M visit is billed on the same day as a 0-day global procedure, the most expensive service is paid at 100% and the others at 80%. CMS had proposed 50% and had proposed including 10- and 90-day globals. It finalized neither.
• Advance care planning. New G-codes G0572 and G0573 for ACP furnished by clinical staff under direct supervision. CPT 99497 and 99498 are now for time the billing practitioner spends personally.
• Shared medical appointments. New coding and payment, with an add-on code for additional time.

Where Caesar Health fits

Getting the modifier right on every visit is a coding job, and it's one more thing to miss at the end of a long clinic day.

• The AI Scribe codes the visit. It drafts the note, suggests the E/M level from the documentation, and adds B1 or B2 based on whether the clinic is flagged as a Shared Savings Program or LEAD participant.
• Chart-close review catches misses. Before a visit closes, Caesar checks the codes against the documentation.
• The quality side runs alongside. For ACO practices, Caesar keeps the care-gap worklist and computes the APP Plus measures B2 is meant to recognize. See MSSP quality measures for 2027 and ACOs and provider networks.