Maybe the law of primacy has confused my understanding of this. I was told a while ago and never thought to question it..

Under 40, 1st class privileges are good for 12 months. After 12 months does that medical grant 2nd class privileges ? (Working as SIC in 121)

Everything I’m reading I am now interpreting as after 12 months you can only use 3rd class privileges.

Was my original understanding incorrect?