OBJECTIVES: The phosphate binders (PBs) sevelamer hydrochloride or carbonate (SH/SC) and lanthanum carbonate (LC) will be included in the Centers for Medicare and Medicaid Services (CMS) bundled payment scheme from 2016. The aim of this study was to determine the inflection point in daily drug dose at which a switch to LC becomes cost-effective in dialysis patients on SH/SC with a high pill burden. METHODS: A Microsoft Excel-based pharmacy budget impact model (BIM) was developed to carry out a comparative analysis of the cost impact of LC versus SH/SC therapy from the standpoint of a US-based dialysis organization. Model assumptions were based on published literature, market research data, and prescription information. User inputs included drug cost, adherence rate, number of patients on dialysis, first-line PB treatment, titration protocols, and serum phosphate target levels. RESULTS: The cost of an initial dose of SH/SC 4800 mg/day was lower than that of LC 1500 mg/day. After a first titration step, SH/SC 7200 mg/day vs LC 2250 mg/day was cost-neutral. Following a second titration step, SH/SC 9600 mg/day vs LC 3000 mg/day exhibited cost savings in favor of LC of $15/day vs SH and $8/day vs SC. The estimated potential cost saving of switching one patient to LC 3000 mg/day compared with up-titration to SH or SC 9600 mg/day is $451 or $228/month, respectively. This equates to an estimated saving of $13.8 million/year for the 4096 patients who were modeled to switch to LC based on utilization data. CONCLUSIONS: BIM analyses indicate that the inflection point at which LC becomes cost-effective is SH/SC 7200 mg/day. Substantial savings in PB costs can be realized by switching patients to LC instead of increasing the SH/SC dose above 7200 mg/day. This strategy has the potential to reduce the overall budgetary impact for US-based dialysis centers under the CMS bundle.