OBJECTIVES:  Budget Impact Analysis (BIA) is an important tool used in pharmaceutical pricing and reimbursement. We compared the BIA methods of the Institute for Clinical and Economic Review (ICER) to those of influential Health Technology Assessment (HTA) agencies. The aim was to determine whether they share similar BIA methods and goals and whether ICER is aligned with ISPOR’s 2012 BIA recommendations. METHODS:  We examined BIA methods guidelines of NICE, SMC, G-BA/IQWiG, PBAC, HAS, and CADTH, comparing them to each other and to ICER’s methodology framework. We used ISPOR’s 2012 BIA report on good practices as a benchmark for comparison. We assessed each set of HTA guidelines and methodologies to determine who conducts the BIA, the perspective of the BIA, and how the analysis is used. RESULTS:  HTA agencies and ISPOR’s guidance are consistent in their BIA approach, requiring assessments which address specific payers and policymakers and using real-world costs and populations. ICER uses a generic perspective, generally assuming wholesale acquisition costs, an unmanaged healthcare system (excluding cost-offsets or other resource considerations), with populations and uptake patterns that lack the specificity and applicability of those used by HTA agencies. ICER also uses a uniform budget cap in its analysis, potentially creating a bias towards lower cost drugs, regardless of effectiveness. ICER uses BIA and cost-effectiveness to determine whether the drug is affordable and provides good value to the healthcare system, and whether discounts are needed for the product-price to be "value based." HTA agencies primarily use BIA to aid in implementing their decisions. CONCLUSIONS:  HTA agencies are more consistent with ISPOR BIA guidance than ICER. ICER’s generic perspective and broad assumptions call into question the validity and usefulness of their BIA analyses, especially when used by ICER to make determinations about value and not, like most HTA agencies, solely to guide implementation.