A terminal apparatus includes a receiver and a transmitter. The receiver receives, from a base station, a downlink assignment index (DAI) that is transmitted by means of a downlink control information (DCI) format. The DAI indicates an accumulative number of a transmitted physical downlink shared channel (PDSCH) included in a group of PDSCHs. A range of the accumulative number of which the DAI is indicative is variably configured. The transmitter, in operation, transmits, to the base station, hybrid automatic repeat request acknowledgement (HARQ-ACK) information based on the DAI.