OBJECTIVES: Chronic Obstructive Pulmonary Disease (COPD) is a prevalent disease with a significant economic burden to the UK National Health Service (NHS). NICE recommends maintenance treatment including inhaled bronchodilator medications, such as long-acting muscarinic antagonists (LAMAs) and long-acting beta-2-agonists (LABAs). The objective of this model was to quantify the budget impact to the NHS of switching patients with moderate to very severe COPD from tiotropium to tiotropium + olodaterol Respimat^®, compared with remaining on tiotropium monotherapy. METHODS: The model used a deterministic individual-level Markov approach to compare scenarios with and without the introduction of tiotropium + olodaterol Respimat^®into the health economy. Patients progressed through the model based on their individual FEV1 values at baseline and their post-treatment FEV1 value over 5 years. Relative treatment effects (estimated from a mixed-treatment comparison) were applied at 2 weeks. Lung function decline after 2 weeks was applied independent of treatment arm but dependant on GOLD stage. Exacerbation risk, health outcomes and costs of COPD management were calculated based on GOLD stage. Cost inputs were taken from published literature. RESULTS: The 5-year budget impact of displacement of tiotropium by tiotropium + olodaterol Respimat^®was a cost-saving of £25.8 million, £2.7 million, £1.6 million, and £0.9 million, in England, Scotland, Wales, and Northern Ireland respectively. These cost-savings were largely driven by a predicted 0.8% reduction in COPD management costs, and a predicted 0.9% reduction in the costs of exacerbation management. CONCLUSIONS: Switching patients with COPD from tiotropium maintenance to tiotropium + olodaterol Respimat^® maintenance therapy has the potential to be cost-saving to the UK NHS. These cost-savings largely result from a predicted reduction in primary and secondary care costs. Whilst treatment switching should be driven by clinical rationale and patient preference, this finding has implications for medicine optimisation in the UK.