How Payer Formulary Changes Affect Biologics Access in 2026

Formulary changes don't send you a calendar invite. A patient who picked up their biologic without a second thought in January can suddenly hit a wall in July — same drug, same diagnosis, same insurance — because the plan moved the medication to a non-preferred tier mid-year and the practice didn't catch it until a pharmacy rejection landed in the queue.

This is increasingly common as payers accelerate biosimilar adoption and restructure their formularies around cost-sharing rather than clinical preference. Understanding how formulary changes work — and when they happen — is the difference between protecting your patients' access and playing catch-up after the fact.

How Formulary Changes Work

Commercial health plans are required by ACA regulations to notify members of certain formulary changes in advance — typically 60 days for drugs being removed from a formulary, and sometimes less for tier changes. In practice, these notices often reach the patient without reaching the provider, which means the first sign a practice sees is a rejection or a call from a confused patient at the pharmacy.

Formulary reviews happen on two timelines:

Annual Open Enrollment Changes

The most significant formulary restructuring happens at the start of each plan year — January 1 for most commercial plans, October 1 for many government programs. This is when plans publish their new formulary tiers, add biosimilar agents, and shift preferred status between originator and biosimilar products.

For biologics, annual changes in 2025 and 2026 have been heavily driven by the expanding FDA biosimilar approvals. As of early 2026, more than 60 biosimilar products are approved in the US. Adalimumab alone has 11 approved biosimilars. When that many interchangeable products exist for a single molecule, payers restructure formulary tiers around them — typically making biosimilars preferred and placing the originator (Humira) at a higher cost-sharing tier or requiring a prior authorization exception to access it.

Mid-Year Changes

Plans reserve the right to make mid-year formulary changes under certain conditions: new FDA approvals, significant price changes, safety updates, or contract renegotiations with manufacturers. The CMS formulary change notification requirements for marketplace plans require 60-day advance notice for non-preferred tier changes and removals. Medicare Advantage plans follow similar rules. But employer-sponsored plans have more flexibility — and mid-year changes in those plans can happen faster.

Mid-year biosimilar additions are the most common source of surprise right now. A plan that didn't have a biosimilar-first policy in January may implement one in April when a new interchangeable biosimilar gets approved and the plan renegotiates its pharmacy benefit.

What Tier Changes Mean for Biologic Access

A drug moving from preferred to non-preferred tier doesn't mean coverage disappears. It means the patient's cost-sharing increases — often significantly — and the drug may now require a step therapy or prior authorization that wasn't required before.

The practical impact depends on the plan design. In some plans, a tier change takes an originator biologic from a $50 copay to a 30–40% coinsurance — which on a drug with a list price of $25,000–$60,000 per year creates a patient out-of-pocket exposure that isn't realistic. Manufacturer copay assistance programs can offset this for commercially insured patients, but those programs don't apply to Medicare or Medicaid patients.

For practices in rheumatology, dermatology, and gastroenterology, the realistic 2026 scenario looks like this: a significant portion of patients on branded biologics will face new prior authorization requirements or non-preferred tier designations as biosimilar-first policies take hold. Some will switch without issue. Others will have documented clinical reasons to stay on their current agent — and those patients need formulary exception requests.

How to Monitor Formulary Changes

Most practices don't have a systematic approach to formulary monitoring. The reality is that tracking formulary changes across 20+ payers for a panel of biologic patients is a genuinely hard operational problem — there's no single feed or notification system that covers all commercial plans.

The most practical approaches:

Annual January review: Pull the formulary for each major payer in your region at the start of each plan year. Flag any biologics you commonly prescribe that changed tier status or added PA requirements.
Patient-level eligibility checks: Run pharmacy benefit eligibility checks before biologic refills for patients you haven't heard from in a while. A patient who refills every 90 days and had no issues in October may have a formulary issue in January.
Pharmacy rejection alerts: Build a workflow where pharmacy rejections on biologic claims trigger same-day notification to the PA team rather than sitting in a queue.
Payer portal subscriptions: Many payers allow providers to subscribe to formulary update notifications via their provider portals. UHC, Aetna, and Cigna all have provider portal notification settings worth checking.

The VA National Formulary is a useful public reference for coverage patterns, and Medicare Part D formulary data is publicly available through CMS — though commercial plan formularies remain payer-specific.

When a Patient's Biologic Gets Moved to Non-Preferred

When this happens mid-therapy, the first question is whether the patient can switch to the preferred biosimilar without clinical risk. Many can — interchangeable biosimilars are approved specifically because they meet the FDA standard for substitution without clinical differences. But "can switch" and "should switch" aren't always the same thing.

Documented reasons to request a formulary exception rather than switch:

Patient has tried the preferred biosimilar previously and experienced adverse effects or inadequate response
Patient has a documented contraindication to a specific formulation or delivery device
Patient is in a period of clinical stability and the provider believes switching creates meaningful transition risk
Interchangeability designation doesn't cover all indications — there are edge cases where the preferred biosimilar isn't approved for the patient's specific indication

Formulary exception requests follow a similar structure to standard prior authorizations — documented clinical rationale, diagnosis codes, and a specific statement explaining why the non-preferred agent is medically necessary. The difference is that the clinical argument is about the specific product rather than the drug class.

Documenting Formulary Exception Requests

A strong formulary exception request does three things. It confirms that the preferred alternative was considered. It explains why it's not appropriate for this specific patient. And it provides clinical evidence that the requested non-preferred agent is working.

The most successful exception requests for stable patients include treatment response documentation — disease activity scores, lab values, patient-reported outcomes — that demonstrate the current agent is achieving good control. Payers are more likely to approve an exception for a patient with documented excellent response on an originator biologic than for a patient whose most recent documentation shows minimal improvement.

This is a place where the ongoing documentation your team captures during routine visits matters. A note from six months ago that quantified disease activity is more useful in an exception request than a narrative statement written the day the exception request is submitted.

Staying Ahead of 2026 Formulary Shifts

The biosimilar expansion is going to continue driving formulary change velocity through 2026 and beyond. The FDA biosimilar pipeline includes agents across oncology, rheumatology, and gastroenterology that will create new preferred-tier dynamics as they launch and payers negotiate rebates.

Practices that treat formulary monitoring as a one-time annual task will be managing reactive problems all year. Practices that build ongoing monitoring into their workflow — ideally with systems that catch changes before a patient's refill fails — are operating in a fundamentally different mode.

Luma's real-time payer requirement research catches current formulary status as part of generating PA documentation. When criteria have shifted — a new step therapy requirement, a biosimilar added to preferred tier — the documentation reflects what the plan actually requires at the time of submission, not what was true six months ago.

For related posts on managing payer-specific documentation requirements, visit the Luma blog.

Sources: FDA Biosimilar Product Information and Approvals (fda.gov/drugs/biosimilars); CMS, Formulary Requirements Guidance for ACA Marketplace Plans (cms.gov); Medicare Interactive, Medicare Part D Formularies overview (medicareinteractive.org); VA National Formulary (pbm.va.gov); IQVIA Institute, "The Use of Medicines in the United States 2024" (iqvia.com); American Journal of Managed Care, "Biosimilar Formulary Placement and Access" 2024 (ajmc.com).