As a rule, an operator's mine-mouth output value for a fiscal year is the portion of the gross value of the operator's annual output that is reasonably attributable to the operation of the mine, minus the following amounts:

• expenses for activities consisting in the crushing, milling, sieving, processing, handling, transportation or storage of a mineral substance from its first accumulation site following its extraction from the mine, and, if applicable, of the processing products obtained;
• expenses for activities consisting in the marketing of the mineral substance and, if applicable, of the processing products obtained;
• general and administrative expenses that relate to the activities referred to in the previous points;
• the amount deducted as a depreciation allowance for class 1A, class 2A, class 3A and class 4A property;
• the amount deducted as a processing allowance.

In addition, adjustments have to be made in calculating the mine-mouth output value in the following situations:

• In the fiscal year, the operator alienates, in favour of a person to whom the operator is not related, gemstones that have not been mixed with other gemstones, if the value of the particular gemstones was taken into consideration in the calculation of the gross value of the operator's annual output for a previous fiscal year that began after December 31, 2013.
• The valuation method that the operator used to determine the gross value of annual output for the fiscal year is different from the one used for the previous fiscal year (the operator must obtain our authorization to change methods).

The above adjustments increase or reduce the mine-mouth output value.