Matching of credit notes with recipient input tax reductions triggers additions and interest where declarations or duplications are absent. Every supplier's credit note must be matched with the recipient's corresponding reduction in input tax credit and checked for duplication, with accepted matches communicated as prescribed. If a supplier's reduction exceeds the recipient's declared reduction or the recipient fails to declare the credit note, the discrepancy is communicated; unrectified discrepancies and duplicative reductions are added to the supplier's output tax liability in specified subsequent returns. The supplier may reclaim added amounts if the recipient declares the credit note within the prescribed period. Interest applies to amounts added for discrepancies or duplications from the date of the original claim, and interest paid may be refunded to the supplier within prescribed limits.