v3.26.1
Credit Risk - Disclosure of ECL Reconciliation (Details) - GBP (£)
£ in Millions
 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Less: Recoveries net of collection costs £ (6) £ (10)
ECL    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Transfers from Stage 1 to Stage 2 0 0
Transfers from Stage 2 to Stage 1 0 0
Transfers to Stage 3 0 0
Transfers from Stage 3 0 0
Transfers of financial instruments 0 0
Net ECL remeasurement on stage transfer 86 93
Change in economic scenarios 22 (8)
Change to ECL models 0 0
Acquisition of TSB 62  
New lending and assets purchased 42 40
Redemptions, repayments and assets sold (96) (89)
Changes in risk parameters and other movements 92 75
Assets written off (131) (101)
Net movement in the period, ECL 77 10
ECL charge to the Income Statement 208 111
Less: Discount unwind (8) (10)
Less: Recoveries net of collection costs 77 4
Total ECL charge to the Income Statement 277 105
Financial instruments not credit-impaired | Subject to 12-month ECL | Stage 1    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Transfers from Stage 1 to Stage 2 (14) (9)
Transfers from Stage 2 to Stage 1 62 63
Transfers to Stage 3 (2) (1)
Transfers from Stage 3 0 4
Transfers of financial instruments 46 57
Net ECL remeasurement on stage transfer (56) (59)
Change in economic scenarios 5 (6)
Change to ECL models 0 0
Acquisition of TSB 62  
New lending and assets purchased 25 21
Redemptions, repayments and assets sold (16) (15)
Changes in risk parameters and other movements (9) (13)
Assets written off 0 0
Net movement in the period, ECL 57 (15)
ECL charge to the Income Statement 57 (15)
Less: Discount unwind 0 0
Less: Recoveries net of collection costs 0 0
Total ECL charge to the Income Statement 57 (15)
Financial instruments not credit-impaired | Subject to Lifetime ECL | Stage 2    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Transfers from Stage 1 to Stage 2 14 9
Transfers from Stage 2 to Stage 1 (62) (63)
Transfers to Stage 3 (21) (25)
Transfers from Stage 3 16 23
Transfers of financial instruments (53) (56)
Net ECL remeasurement on stage transfer 74 69
Change in economic scenarios 16 2
Change to ECL models 0 0
Acquisition of TSB 0  
New lending and assets purchased 14 16
Redemptions, repayments and assets sold (35) (42)
Changes in risk parameters and other movements 11 (6)
Assets written off 0 0
Net movement in the period, ECL 27 (17)
ECL charge to the Income Statement 27 (17)
Less: Discount unwind 0 0
Less: Recoveries net of collection costs 0 0
Total ECL charge to the Income Statement 27 (17)
Financial instruments credit-impaired | Subject to Lifetime ECL | Stage 3    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Transfers from Stage 1 to Stage 2 0 0
Transfers from Stage 2 to Stage 1 0 0
Transfers to Stage 3 23 26
Transfers from Stage 3 (16) (27)
Transfers of financial instruments 7 (1)
Net ECL remeasurement on stage transfer 68 83
Change in economic scenarios 1 (4)
Change to ECL models 0 0
Acquisition of TSB 0  
New lending and assets purchased 3 3
Redemptions, repayments and assets sold (45) (32)
Changes in risk parameters and other movements 79 94
Assets written off (118) (101)
Net movement in the period, ECL (5) 42
ECL charge to the Income Statement 113 143
Less: Discount unwind (8) (10)
Less: Recoveries net of collection costs 81 4
Total ECL charge to the Income Statement 186 137
POCI | POCI    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Transfers from Stage 1 to Stage 2 0  
Transfers from Stage 2 to Stage 1 0  
Transfers to Stage 3 0  
Transfers from Stage 3 0  
Transfers of financial instruments 0  
Net ECL remeasurement on stage transfer 0  
Change in economic scenarios 0  
Change to ECL models 0  
Acquisition of TSB 0  
New lending and assets purchased 0  
Redemptions, repayments and assets sold 0  
Changes in risk parameters and other movements 11  
Assets written off (13)  
Net movement in the period, ECL (2)  
ECL charge to the Income Statement 11  
Less: Discount unwind 0  
Less: Recoveries net of collection costs (4)  
Total ECL charge to the Income Statement 7  
–Stage 1 | Financial instruments not credit-impaired | Subject to 12-month ECL    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Transfers from Stage 1 to Stage 2 (7,124) (5,143)
Transfers from Stage 2 to Stage 1 3,806 4,926
Transfers to Stage 3 (171) (123)
Transfers from Stage 3 0 8
Transfers of financial instruments (3,489) (332)
Net ECL remeasurement on stage transfer 0 0
Change in economic scenarios 0 0
Change to ECL models 0 0
Acquisition of TSB 41,018  
New lending and assets purchased 35,868 30,547
Redemptions, repayments and assets sold (19,750) (16,080)
Changes in risk parameters and other movements (9,507) (4,472)
Assets written off 0 0
Net movement in the period 44,140 9,663
–Stage 2 | Financial instruments not credit-impaired | Subject to Lifetime ECL    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Transfers from Stage 1 to Stage 2 7,124 5,143
Transfers from Stage 2 to Stage 1 (3,806) (4,926)
Transfers to Stage 3 (416) (643)
Transfers from Stage 3 183 340
Transfers of financial instruments 3,085 (86)
Net ECL remeasurement on stage transfer 0 0
Change in economic scenarios 0 0
Change to ECL models 0 0
Acquisition of TSB 0  
New lending and assets purchased 288 294
Redemptions, repayments and assets sold (2,543) (1,990)
Changes in risk parameters and other movements 77 191
Assets written off 0 0
Net movement in the period 907 (1,591)
–Stage 3 | Financial instruments credit-impaired | Subject to Lifetime ECL    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Transfers from Stage 1 to Stage 2 0 0
Transfers from Stage 2 to Stage 1 0 0
Transfers to Stage 3 587 766
Transfers from Stage 3 (183) (348)
Transfers of financial instruments 404 418
Net ECL remeasurement on stage transfer 0 0
Change in economic scenarios 0 0
Change to ECL models 0 0
Acquisition of TSB 0  
New lending and assets purchased 25 27
Redemptions, repayments and assets sold (653) (440)
Changes in risk parameters and other movements 119 107
Assets written off (219) (242)
Net movement in the period (324) (130)
POCI | POCI    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Transfers from Stage 1 to Stage 2 0  
Transfers from Stage 2 to Stage 1 0  
Transfers to Stage 3 0  
Transfers from Stage 3 0  
Transfers of financial instruments 0  
Net ECL remeasurement on stage transfer 0  
Change in economic scenarios 0  
Change to ECL models 0  
Acquisition of TSB 467  
New lending and assets purchased 0  
Redemptions, repayments and assets sold (7)  
Changes in risk parameters and other movements (3)  
Assets written off (4)  
Net movement in the period 453  
Exposures    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Transfers from Stage 1 to Stage 2 0 0
Transfers from Stage 2 to Stage 1 0 0
Transfers to Stage 3 0 0
Transfers from Stage 3 0 0
Transfers of financial instruments 0 0
Net ECL remeasurement on stage transfer 0 0
Change in economic scenarios 0 0
Change to ECL models 0 0
Acquisition of TSB 41,485  
New lending and assets purchased 36,181 30,868
Redemptions, repayments and assets sold (22,953) (18,510)
Changes in risk parameters and other movements (9,314) (4,174)
Assets written off (223) (242)
Net movement in the period 45,176 7,942
Cost | –Stage 1 | Financial instruments not credit-impaired | Subject to 12-month ECL    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Beginning balance 272,629 259,883
Ending balance 316,769 269,546
Cost | –Stage 2 | Financial instruments not credit-impaired | Subject to Lifetime ECL    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Beginning balance 18,524 21,218
Ending balance 19,431 19,627
Cost | –Stage 3 | Financial instruments credit-impaired | Subject to Lifetime ECL    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Beginning balance 2,340 2,759
Ending balance 2,016 2,629
Cost | POCI | POCI    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Beginning balance 0  
Ending balance 453  
Cost | Exposures    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Beginning balance 293,493 283,860
Ending balance 338,669 291,802
Accumulated impairment | ECL    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Beginning balance (812) (869)
Ending balance (889) (879)
Accumulated impairment | Financial instruments not credit-impaired | Subject to 12-month ECL | Stage 1    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Beginning balance (157) (153)
Ending balance (214) (138)
Accumulated impairment | Financial instruments not credit-impaired | Subject to Lifetime ECL | Stage 2    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Beginning balance (301) (359)
Ending balance (328) (342)
Accumulated impairment | Financial instruments credit-impaired | Subject to Lifetime ECL | Stage 3    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Beginning balance (354) (357)
Ending balance (349) £ (399)
Accumulated impairment | POCI | POCI    
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]    
Beginning balance 0  
Ending balance £ 2