I believe that if you have a joint SGK policy and one of you starts to receive a state pension then the joint policy ends and you have to have two 'single' policies at TL614 each.
When we had SGK - we paid one premium as I was retired but my wife was only 54 - we would continue paying one premium until my dependent (my wife) had her state pension at age 67 and then she would have to pay - so double from that point. Extremely good deal for us.