From 7 February (including tickets purchased before that date), you can cancel or exchange a free SNCF ticket (TGV, Intercités) up to 6 days before departure, instead of 3 days before departure.

From 6 days before departure, the exchange or refund fee increases from €15 to €19 for domestic and international Inoui TGVs (excluding LYRIA TGVs) and from €12 to €15 maximum for mandatory reservation trains (Bordeaux-Toulouse-Marseille, Paris-Orléans-Limoges-Toulouse, Paris-Clermont-Ferrand).

On the other hand, there is no change for Ouigo trains: tickets, non-cancellable and non-refundable, can be exchanged or modified online, for a fee of 10 € per trip and per traveler, plus any fare difference, up to 30 minutes before the train leaves.