For Lease contract types, this field displays the financial expenses in the contract currency for a given period, which is equal to the fee minus the financial amortization. You can modify this amount.
For Rent contract types, this field represents the interest portion of the lease payment amount that is already stored in the Rental amount column for each period and month. The value in the Financial cost column is not included when calculating the current values and rights of use. This amount is not calculated from the contract characteristic; you need to enter or import it manually.