Prerequisites
The earnings and deductions that you use to pay average salary must have a calculation rule of Amount, where the amount is calculated by the average salary resolution formula, MD FM VALOR MEDIA.
To define that an Average to be resolved belongs to the 13th salary calculation, use the Supporting Element Overrides page of the Earnings or Deductions component to set variable MD VR MEDIA 13 to 1 (one). This setting enables the system to prorate the amount according to the number of months worked.