Schemes require pre-auth for: planned hospital admissions, MRI/CT scans, oncology, chronic medication, certain specialist procedures, and some specialised radiology. You (or your provider) must call or submit before the treatment. In emergencies, you have 24 to 72 hours after admission. Without pre-auth, schemes typically pay only 70 to 80% of DHR or refuse cover entirely. The hospital usually triggers it but always confirm; don't assume it was done.
SA example: You need a knee operation. Your specialist must obtain authorisation 48 hours before admission. Without it, the scheme pays only 70%, so you owe 30% of every hospital, anaesthetist, and theatre charge.