The invention concerns a method for deactivating a payment module attachable to a communications terminal, comprising: a phase for deactivating comprising at least one step for erasing the main memory of said payment module with the exception of a non-volatile memory zone in which an encryption key k is stored, said encryption key k being available only when said main memory is empty; a phase for verifying comprising: a step for verifying that said main memory is empty, delivering a positive or negative result of verification; if said result of verification is positive: a step for computing a response to a challenge preliminarily received by said payment module from an entity distinct from said payment module, said computation being implemented by means of said encryption key k; a step for transmitting said response to said entity.