OBJECTIVES: Upper limb spasticity (ULS) secondary to upper motor neurone lesions has a considerable patient and caregiver burden, particularly with regards to pain, activities of daily living and personal care. BotulinumtoxinA (BoNT-A) injections are effective in treating ULS. We developed a budget impact model (BIM) to assess different BoNT-A treatments available in the UK for reducing ULS. We also assessed annual costs of treating each ULS patient with BoNT-A or best supportive care (BSC). METHODS: The BIM was developed from the UK NHS (National Health Service) and Personal and Social Services (PSS) perspective. The status quo scenario assumed the three BoNT-As, Dysport® (abobotulinumtoxinA), Botox® (onabotulinumtoxinA), or Xeomin® (incobotulinumtoxinA), are used in 33%, 52% and 15%, respectively, of patients  with ULS receiving BoNT-A in the UK. The new market share scenario assumed an increased proportional use of abobotulinumtoxinA (to 73% in year 5) compared to other interventions. The patients were modelled over a 5-year horizon. Epidemiologic data inputs were from published sources. Unit costs for BoNT-As, other healthcare costs and non-medical costs came from the British National Formularyand PSS. Resource-use inputs were obtained from UK clinicians. One-way sensitivity analyses for model inputs were conducted. RESULTS: Total care costs were decreased by between £425,765 in year 2 and £1,854,601 in year 5 by shifting market share to abobotulinumtoxinA. In the base-case scenario, BSC (no BoNT-A treatment) or with incobotulinumtoxinA or onabotulinumtoxinA cost more per patient per year than abobotulinumtoxinA. Sensitivity analyses showed that number of patients treated with BoNT-As, time-to-re-injection, and dose per injection of abobotulinumtoxinA and onabotulinumtoxinA were the most influential parameters on budget impact, impacting both drug acquisition costs and physician visits. CONCLUSIONS: Study findings suggest that increased use of abobotulinumtoxinA compared with incobotulinumtoxinA and onabotulinumtoxinA for ULS in the UK could potentially reduce total treatment costs.