The saved money and the payroll for new money are both in dollars per year, not one-time costs. So the additional premium needs to be 10%, not 5%, to erase the

The saved money and the payroll for new money are both in dollars per year, not one-time costs. So the additional premium needs to be 10%, not 5%, to erase the benefits, and it doesn't matter how many years you look at. (I'm ignoring one-time costs like severance pay and signing/relocation bonuses which I don't think were the point of your message, and also the elasticity effect where you can pay existing workers the same even if it costs more to hire new ones. And I agree with your point in general that this is not a sensible way to save money, I just think your numbers are wrong).