Article 128 sets a procedural limit on the 'Corresponding Adjustment' mentioned in Article 127. Such an adjustment is not automatic; the second party in the transaction must submit a formal written request to the Tax Authority. This request must be filed within twelve months from the date the first party received their tax assessment containing the initial transfer pricing adjustment under Article 126. This strict timeline ensures that adjustments for both parties are resolved within a reasonable period and that the Authority is not forced to re-open historical tax files indefinitely.