Yes, with a smart meter you will be billed on actual consumption. However, smart meters work in measuring 15 minute intervals. If even one of those intervals is missed for a billing period (for example, because a full billing period hasn't passed since the meter was installed, or there was a temporary technical issue, the bill will be shown as "estimated" for the entire period, even if only a tiny portion of the usage was actually estimated. Of course, once an accurate reading is received, you'll only be charged for actual consumption.
