- Registrars — systems with a simplified calculation kernel. Such systems can calculate only "forward". To introduce a recalculation the operator assistance needed, the operator does it manually and inputs the results into the billing system. Apart from manual recalculations the disadvantage of such systems is the absence of calculation history.
- Half-automatic – systems where complete (re)calculation or its part is done automatically. This type completely or partially eliminates the human factor in calculations, but in order to make a recalculation the operator has to perform a lot of preliminary manual work: input recalculation period, cancel accruals, cancel the bill, perform new accruals, form a new bill etc.
- Automatic — systems which can perform calculations and recalculations automatically. Software applications of this type perform all calculations automatically once the operator changes initial data which balance depends on. Recalculation can be performed without operator when new data are received: input of metering measurements from a file of paid notices, data via SMS or Internet, import of telemetric system readings… The results are shown in the balance list for current month. The complexity of making of such systems is a disadvantage, but to work in such a system is easy and convenient.