With many types of the UK visas you have to pay immigration health surcharge (IHS). IT is a significant burden and has to be paidby many visa applicants, at the time of your application or booking your appointment. When applying by post you have to pay IHS online before sending your application. The upside is that once you have paid IHS and been granted the visa you are eligible for use of NHS services. In order to do so, you may be asked to present your biometric residence permit. Or use digital share code if you were issued with electronic visa.
UK government website provides a list of types of visa that require NHS surcharge payment. The cost of IHS can add substantially to the cost of visa. It is crucial to be aware of the full amount due as the visa application will be refused if a correct amount is not paid. The amount of current NHS
