Your monthly lease payment is calculated based on factors like the vehicle’s price, the duration of the lease, the estimated residual value of the vehicle at the end of the lease, and your annual mileage allowance, it also takes into consideration like the cost of borrowing, i.e. interest rates which can fluctuate on a monthly basis. However, once your lease agreement has been agreed, your costs will be fixed for the duration of the contract, the only factors that may change are if the government change VAT or road taxes, if these change, you will be liable for any additional charges if they increase, and you will also benefit if they decrease although this is unlikely.