Objectives The Salford Lung Study in asthma (SLS asthma) is a 12-month, open-label randomised clinical trial comparing clinical effectiveness of initiating once-daily inhaled combination of fluticasone furoate/vilanterol (FF/VI) 184/22 mcg or 92/22 mcg, with continuing optimized usual care (UC) with inhaled corticosteroids (ICS) alone, or in combination with a long-acting β2-agonist (ICS/LABA), in asthmatic patients followed in primary care in the UK. The objective of the analysis is to estimate the economic impact of these results when applied in Spain. Methods A 1-year cost-consequence model was populated with SLS asthma, adopting the Spanish National Health System (NHS) perspective. 775,900 of diagnosed asthmatic patients ≥ 18 years old currently managed with UC in Spain were included in the analysis. Effectiveness data included the percentage of patients per Asthma Control Test (ACT) category at 24 and 52 weeks from SLS asthma. Direct costs (pharmacological and per ACT category) were estimated from Spanish public sources and literature (€, 2018). Base case analysis assumed an increased use of FF/VI from 10 to 20% within 1 year. One-way sensitivity analyses were performed. Results Within the 775,900 asthmatic patients analysed, substitution of UC with FF/VI was associated with reduced costs due to ACT improvement, leading to potential total annual savings of €4,927,672. Sensitivity analyses ranged from €6,012,975 to €14,783,015 cost savings associated with FF/VI. An analysis considering patients only on ICS/LABA showed potential cost savings of €8,207,448. Conclusions The improved asthma control for FF/VI compared with UC observed in SLS asthma could be translated into potential savings for the Spanish NHS. These results may be useful for decision makers.