Article 61 specifies the instances where a Registrant must adjust their Output Tax after the supply date. These include: cancellation of the supply, a change in the supply's tax treatment, an alteration of the previously agreed consideration, the return of goods or services, or an error in charging tax. To perform an adjustment, specific conditions must be met, primarily that the Output Tax amount on the Tax Invoice, or as reported in a Tax Return, does not match the tax that should have been charged following one of the specified events. The article also provides a specific exclusion for place-of-supply reclassifications under Article 27.