Prescribing is one of the most critical decision-making processes in patient care, serving as the final link between clinical diagnosis and therapeutic intervention. Inaccurate or inappropriate prescribing can lead to medication errors, poor therapeutic outcomes, and increased healthcare costs. Within structured healthcare systems such as the NHS, prescribing practices are guided and regulated through the use of formularies—approved lists of medicines designed to support evidence-based, safe, and cost-effective treatment choices. As a medico-legal document, a prescription must be accurate, complete, and legible to ensure optimal patient care and minimize drug-related risks. Previous studies highlight that adherence to established prescribing guidelines and formularies improves clinical outcomes while reducing unnecessary hospitalizations and adverse drug events. Formularies play a crucial role in standardizing treatment protocols, promoting rational drug use, and minimizing harmful drug interactions. In the United Kingdom, the British National Formulary (BNF) serves as a comprehensive reference for healthcare professionals, while individual NHS Trusts frequently develop local formularies that reflect institutional policies, therapeutic priorities, and economic considerations. Monitoring prescribing practices against these formularies is therefore an essential quality assurance strategy. Evaluating formulary compliance among outpatient prescriptions provides insight into prescribing behavior, identifies potential deviations from recommended practices, and supports the development of interventions aimed at improving medication safety, clinical effectiveness, and resource utilization within NHS healthcare settings.