v3.26.1
Income Taxes (Breakdown of Net Operating Loss Carryforwards by Tax Jurisdiction) (Detail) - JPY (¥)
¥ in Millions
Mar. 31, 2026
Mar. 31, 2025
Operating Loss Carryforwards [Line Items]    
Deferred tax assets, operating loss carryforwards [1],[2] ¥ 134,675 ¥ 151,390
Operating loss, Valuation allowance (125,000) (125,000)
Deferred tax assets, net of valuation allowance 10,000 26,000
Japan    
Operating Loss Carryforwards [Line Items]    
Deferred tax assets, operating loss carryforwards 31,000 [3] 54,000 [4]
Operating loss, Valuation allowance (26,000) [3] (35,000) [4]
Deferred tax assets, net of valuation allowance 5,000 [3] 20,000 [4]
United States of America    
Operating Loss Carryforwards [Line Items]    
Deferred tax assets, operating loss carryforwards 5,000 5,000
Operating loss, Valuation allowance (1,000) 0
Deferred tax assets, net of valuation allowance 4,000 5,000
United Kingdom    
Operating Loss Carryforwards [Line Items]    
Deferred tax assets, operating loss carryforwards [5] 98,000 90,000
Operating loss, Valuation allowance [5] (98,000) (90,000)
Deferred tax assets, net of valuation allowance [5] 0 0
Others    
Operating Loss Carryforwards [Line Items]    
Deferred tax assets, operating loss carryforwards 1,000 2,000
Operating loss, Valuation allowance 0 0
Deferred tax assets, net of valuation allowance ¥ 1,000 ¥ 2,000
[1] The amount includes ¥11,423 million and ¥1,613 million related to MHSC’s net operating loss carryforwards resulting mainly from the organizational restructuring of certain foreign subsidiaries as of March 31, 2025 and 2026, respectively. The tax effect of the net operating loss carryforwards as of March 31, 2025 is substantially offset by ¥4,408 million of valuation allowance as a result of considering all available evidence regarding sources of future taxable income including historical trends in taxable income in the preceding periods and forecasted taxable income.
[2] The amount includes ¥24,943 million and ¥24,852 million related to MHFG’s net operating loss carryforwards resulting mainly from intercompany capital transactions in relation to the share buyback conducted by MHSC as of March 31, 2025 and 2026, respectively. The tax effect of the net operating loss carryforwards is fully offset by ¥24,943 million and ¥24,852 million, respectively, of valuation allowance as a result of considering all available evidence regarding sources of future taxable income including historical trends in taxable income in the preceding periods and forecasted taxable income.
[3] ¥25 billion of the Japan deferred tax assets of ¥31 billion is related to MHFG, which is fully offset by a valuation allowance, and will mostly expire during the fiscal year ending March 31, 2032. ¥3 billion of the Japan deferred tax assets of ¥31 billion is related to MHBK and will mostly expire during the fiscal year ending March 31, 2034.
[4] ¥25 billion of the Japan deferred tax assets of ¥56 billion is related to MHFG, which is fully offset by a valuation allowance, and will mostly expire during the fiscal year ending March 31, 2032. ¥16 billion of the Japan deferred tax assets of ¥56 billion is related to MHBK and will mostly expire during the fiscal year ending March 31, 2034.
[5] The United Kingdom net operating loss carryforwards may be carried forward indefinitely for tax purposes.