OBJECTIVES:  Tumor necrosis factor (TNF)-a inhibitors such as infliximab, etanercept and adalimumab are used in the treatment of rheumatoid arthritis. As biosimilars for these drugs emerge, we seek to develop an Excel-based, interactive tool that estimates the discount rate required in order for any new biosimilar to be the least expensive treatment option, accounting for all relevant treatment costs, from a healthcare system’s perspective in the Nordic setting. METHODS:  The output of a structured review of published literature was used to estimate mean annual treatment (drug, healthcare utilization and monitoring/admin) costs (SEK 2015) for the biologic treatments. An Excel-based tool was then developed in order to identify the least expensive option in Sweden and to calculate what discount would need to be applied to the price of any new biosimilar drug in order for the treatment’s total costs to be equal to those of the least expensive option. RESULTS:  The least expensive comparator by total costs in Sweden in 2015 was identified to be the infliximab biosimilar Remsima™ with a 39.01% discount on the originator Remicade®. For the full treatment cost of an etanercept or adalimumab biosimilar to be equal to that of Remsima™, discounts of 26% and 28% respectively would be required. Should current discounts reflect those in the Norwegian setting in 2015, where a 69% discount was applied to Remsima™, the required discounts for etanercept and adalimumab biosimilars would be 58% and 57% respectively. If only drug prices were accounted for, the required discounts would increase to 35% and 40% in the Swedish scenario and 67% and 69% in the Norwegian scenario. CONCLUSIONS:  All relevant treatment costs should be accounted for when calculating what drug price discount would be needed for a biosimilar of a given TNF-a inhibitor to be the least expensive option for a healthcare system.