When and how is the difference between the advance payments and actual utility consumption, such as gas/water/electricity, settled?

Annually or at the end of the rental period. Some landlords opt to do this at a fixed time in the year and others do it for the first time after a full year of rental. The tenant’s actual consumption is calculated based on the initial and final meter readings and current utility rates. The advance payments are deducted from this and the difference is either reimbursed to or paid by the tenant. If the individual residential units do not each contain a separate meter, a fair allocation formula is applied.