Article 21 sets the obligations for the submission and amendment of Tax Returns under the Bahrain DMTT. The Filing Constituent Entity must submit a return for each fiscal year within the timeframe specified by the Regulations. If errors are discovered, an amended return must be filed immediately. Notably, pursuant to Paragraph C, if the MNE Group fails the Article 3 Revenue Test for a specific year, the entity must notify the Bureau and may then be exempt from filing a return for that year. The Regulations will further specify the required documentation, forms, and standards for these submissions to ensure full transparency.