Given the prominence of online teaching over the last few years, mobile instant messaging (MIM) has grown in importance for students studying English outside of class. Applications like WhatsApp have the potential to provide language learners the opportunity to practise communicative strategies while receiving feedback from a teacher. To explore feedback provision in a MIM context, the present study examined the experience of 11 English as a foreign language learners in Spain while they received two types of delayed corrective feedback in a WhatsApp group, used as an extension of their online B2 English course. For five weeks students completed weekly language-based tasks from which errors were selected and received feedback either during the tasks or after the series of tasks were completed. The chat transcript was analysed to give a holistic view of the interaction within the group, and students' perspectives on the feedback provision were gathered through semi-structured interviews and questionnaires. Overall students were more responsive to, more successful at, and preferred, repairing their own errors while receiving correction during the tasks. Addressing the lack of research on language learning in MIM contexts and different approaches to corrective feedback timing, this study contributes insight into future research and pedagogical implications for practitioners.