Article 52 specifies the methodology for calculating the value of annual supplies to determine VAT registration thresholds. The calculation can be based on either a retrospective or prospective twelve-month period. The retrospective method considers the total value of non-exempt supplies made in the previous eleven months plus the current month. The prospective method evaluates expected non-exempt supplies for the following eleven months plus the current month. The total value of supplies includes taxable supplies (excluding capital assets), supplies received under the reverse charge mechanism, and certain intra-GCC supplies. Member States are also authorised to aggregate business revenues of Related Persons for mandatory registration.