Lots has been studied and even reported on the decision criteria involved in pulling the trigger on a public finance refunding. When is the right time? What bonds do I choose? What savings target do I use? The old rule of thumb that present value (pv) savings should be at least 3% of refunded par is taking some criticism which I won't repeat here. Suffice it to say it's a threshold originally conceived by bankers and as such, the bar for a "Go" decision is not very high. I personally think it's age discrimination; this calculation does have a good three decades under the belt...