In this paper we pointed out a hidden inequality in accounting for trade-related emissions in the presence of border carbon adjustment. Under a domestic carbon pricing policy, producers pay for the carbon costs in exchange for the right to emit. Under border carbon adjustment, however, the exporting country pays for the carbon costs of their exports to the importing country but not be given any emission credits. As a result, export-related emissions will be remained in the national inventory of the exporting country based on the UNFCCC inventory approach. This hidden inequality is important to climate policy but has not yet been pointed out. To address this issue we propose a method of National Inventory Adjustment for Trade, by which export-related emissions will be deducted from the national inventory of the exporting country and added to the national inventory of the importing country which implements border carbon adjustment. To assess the policy impacts, we simulated a carbon tax policy with border tax adjustment for Japan using a multi-region computable general equilibrium model. The results indicate that with the National Inventory Adjustment for Trade, both Japan's national inventory and the carbon leakage effects of Japan's climate policy will be greatly different. (C) 2013 Elsevier Ltd. All rights reserved.