Schemes can load up to 75% onto your monthly contribution — for life — if you join after age 35 without continuous prior cover. The good news: the formula is fixed by regulation, so you can plan around it.
Yes — once applied it remains for as long as you stay on a medical scheme. It is recalculated only if you change schemes.
Joining before age 35 avoids it entirely. After 35, providing proof of continuous prior cover (e.g. an employer scheme certificate) reduces or eliminates the loading.