Congressional debate often reduces a policy’s fiscal impact to one number: how much it is expected to save or cost over ten years.

That number can determine whether legislation advances, how it is designed and how stakeholders advocate for or against it.

But a score is not a fixed prediction. It is an estimate based on the policy language, available evidence and assumptions about how stakeholders will respond.

Recent Congressional Budget Office (CBO) revisions involving Medicare drug policy show why these estimates are becoming more difficult to produce and why understanding what sits behind the headline number is increasingly important.

Why it matters: The score can shape the policy  

CBO scores influence whether a proposal is considered politically and procedurally viable, which provisions are changed or removed, what offsets lawmakers need and how stakeholders frame the policy’s potential benefits and tradeoffs.

The challenge is that health policies rarely operate in isolation. A change in one part of Medicare can alter incentives and behavior elsewhere, sometimes in ways that cannot be fully anticipated before implementation.

A score may be a critical input into policy and advocacy strategy, but the number alone does not reveal which assumptions drive the result, where uncertainty is greatest or where unintended consequences may emerge.

Zooming in: Two recent revisions, two sources of uncertainty

Technical details can change the estimate

In July 2025, CBO estimated that changes to the Inflation Reduction Act’s (IRA’s) orphan-drug exemption would increase federal spending by $4.9 billion over ten years.

After outside experts raised questions about additional products that could be affected, CBO conducted further analysis and revised the estimate to $8.8 billion. CBO also found that the cost could range from $6.7 billion to $10.9 billion, depending partly on how the Centers for Medicare & Medicaid Services (CMS) treats different formulations of affected products.

What this shows: Understanding a proposal’s effects requires more than interpreting its statutory language. It also requires detailed knowledge of the products, programs and markets the policy would affect.

The market may respond differently than expected

In 2022, CBO estimated that the IRA’s major Medicare Part D drug provisions would reduce federal deficits by $129 billion through 2031. CBO now projects that those provisions, taken together, will increase deficits over the same period because:

  • Negotiated prices produced smaller initial net-price reductions than CBO anticipated.
  • Higher inflation reduced projected savings from manufacturer inflation rebates.
  • Part D costs and prescription drug use grew more rapidly than expected.
  • Plan bids, and the resulting federal subsidies, were substantially higher than projected.

What this shows: Policy can change behavior throughout the health care system: patients may use more medicines when out-of-pocket costs decline, plans may adjust bids, formularies and utilization management, and manufacturers may change pricing and market strategies. These effects are difficult to isolate and even harder to predict before a policy takes effect.

The takeaway: One score is not enough

The lesson is not that scoring has become less useful. Rather, a single point estimate may provide false precision when a policy depends on uncertain implementation decisions and behavioral responses.

A more decision-useful analysis should identify:

  • The assumptions with the greatest influence on the estimate
  • The evidence supporting those assumptions, including evidence gaps
  • Product or market details that could change the result
  • Unresolved agency implementation decisions
  • Potential stakeholder responses
  • Plausible alternative outcomes

Instead of relying on one estimate, policymakers and stakeholders should examine a central scenario alongside credible higher- and lower-impact scenarios. Sensitivity analysis can show how the result changes when critical assumptions shift.

The goal is not to predict the future with perfect accuracy. It is to understand the conditions under which a policy is likely to achieve its objectives and where it could produce unintended consequences.

From scoring to strategy

CBO-style scoring can inform strategy well beyond the headline budget impact.  

A thoughtful analysis can help stakeholders identify major cost drivers, test policy modifications, anticipate questions from policymakers, strengthen the evidence supporting a proposal and prepare for alternative implementation approaches.

It can also support advocacy messages that acknowledge uncertainty while clearly explaining the policy’s rationale and likely effects.

The bottom line

As health policies become more interconnected, scoring them will become more difficult. That makes rigorous analysis more important, not less.

The most useful CBO-style analysis connects the number to the policy choices behind it. It considers multiple plausible scenarios, makes uncertainty visible and gives policymakers and stakeholders a stronger foundation for deciding how to design, defend or improve a proposal.

Go deeper:

To learn more about Reservoir's CBO-style scoring and other analytical capabilities, contact Ashley Flint at aflint@reservoirhealth.com.

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