The Immigration Health Surcharge (IHS) number is not used by the NHS for administrative purposes and there is no advantage in printing it on the biometric residence permit (BRP).
Surcharge payers can use their BRP to evidence their status as part of the eligibility checks carried out by the NHS. The Home Office shares data with the NHS in England on those who have paid the surcharge, or who are exempt from doing so and are entitled to free NHS care. It also provides checking services for the NHS in other parts of the UK. These services help the NHS establish whether a patient is chargeable.