v3.25.2
Deferred tax assets (DTA) (net) / deferred tax liabilities (DTL) (net) - Summary of Deferred Tax Liabilities (Net) (Detail)
₨ in Millions, $ in Millions
Mar. 31, 2025
INR (₨)
Mar. 31, 2025
USD ($)
Mar. 31, 2024
INR (₨)
Deferred Tax Liabilities [Abstract]      
Deferred tax liabilities ₨ 24,481 $ 287 ₨ 18,705
Deferred Tax Assets [Abstract]      
Deferred tax assets 7,073 83 5,556
Net Deferred Tax Liabilities      
Deferred Tax Assets [Abstract]      
Deferred tax liabilities (net) 24,481 287 18,705
Deferred Tax Liabilities | Net Deferred Tax Liabilities      
Deferred Tax Liabilities [Abstract]      
Deferred tax liabilities 70,043 820 62,455
Deferred Tax Liabilities | Net Deferred Tax Liabilities | Compound financial instruments      
Deferred Tax Liabilities [Abstract]      
Deferred tax liabilities 195 2 217
Deferred Tax Liabilities | Net Deferred Tax Liabilities | Mark to market of derivative instruments      
Deferred Tax Liabilities [Abstract]      
Deferred tax liabilities 797 9 842
Deferred Tax Liabilities | Net Deferred Tax Liabilities | Difference in written down value of PPE as per books of account and tax laws      
Deferred Tax Liabilities [Abstract]      
Deferred tax liabilities 68,256 799 60,518
Deferred Tax Liabilities | Net Deferred Tax Liabilities | Unamortized ancillary borrowing cost      
Deferred Tax Liabilities [Abstract]      
Deferred tax liabilities 168 2 182
Deferred Tax Liabilities | Net Deferred Tax Liabilities | Right of use asset      
Deferred Tax Liabilities [Abstract]      
Deferred tax liabilities 561 7 653
Deferred Tax Liabilities | Net Deferred Tax Liabilities | Others      
Deferred Tax Liabilities [Abstract]      
Deferred tax liabilities 66 1 43
Deferred Tax Assets | Net Deferred Tax Liabilities      
Deferred Tax Assets [Abstract]      
Deferred tax assets 45,562 533 43,750
Deferred Tax Assets | Net Deferred Tax Liabilities | Mark to market of derivative instruments      
Deferred Tax Assets [Abstract]      
Deferred tax assets 14 0 30
Deferred Tax Assets | Net Deferred Tax Liabilities | Unamortized ancillary borrowing cost      
Deferred Tax Assets [Abstract]      
Deferred tax assets 9 0 5
Deferred Tax Assets | Net Deferred Tax Liabilities | Provision for decommissioning costs      
Deferred Tax Assets [Abstract]      
Deferred tax assets 1,685 20 1,715
Deferred Tax Assets | Net Deferred Tax Liabilities | Expected credit losses      
Deferred Tax Assets [Abstract]      
Deferred tax assets 399 5 370
Deferred Tax Assets | Net Deferred Tax Liabilities | Losses and unabsorbed depreciation available for offsetting against future taxable income      
Deferred Tax Assets [Abstract]      
Deferred tax assets 39,487 462 37,168
Deferred Tax Assets | Net Deferred Tax Liabilities | Unused tax credt (Minimum alternate tax)      
Deferred Tax Assets [Abstract]      
Deferred tax assets 2,722 32 2,867
Deferred Tax Assets | Net Deferred Tax Liabilities | Lease Liabilities      
Deferred Tax Assets [Abstract]      
Deferred tax assets 737 9 791
Deferred Tax Assets | Net Deferred Tax Liabilities | Government grant (viability gap funding)      
Deferred Tax Assets [Abstract]      
Deferred tax assets 355 4 453
Deferred Tax Assets | Net Deferred Tax Liabilities | Others      
Deferred Tax Assets [Abstract]      
Deferred tax assets ₨ 154 $ 2 ₨ 351