v3.26.1
Income tax - Narrative (Details) - EUR (€)
€ in Thousands
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]      
Deferred tax liabilities € 17,616 € 1,584 € 444
Deferred tax assets 241,894 155,715 116,006
Net deferred tax liabilities 5,848 0 0
Unused tax losses for which no deferred tax asset recognised 911,776 609,390 459,752
Royalty certificates      
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]      
Deferred tax liabilities 17,208 0 0
Deferred tax assets   1,427 0
Royalty certificates | France      
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]      
Deferred tax assets 11,720    
Abivax LLC      
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]      
Unused tax losses for which no deferred tax asset recognised € 1,083 € 112 € 38