Certain aspects of the present disclosure provide techniques for demodulation reference signal (DMRS) time domain bundling and multiple codeword transmission and processing in new radio (NR) systems. A method by a transmitting device includes transmitting multiple codewords to a receiving device in a first period, each of the multiple codewords transmitted using a different set of one or more DMRS ports. The transmitting device determines to retransmit one or more of the multiple codewords and, for each of the multiple codewords to be retransmitted, the set of DMRS ports for retransmission of the codeword. The determination is based, at least in part, on whether DMRS time domain bundling is configured. The transmitting device retransmits the one or more codewords in a second period based on the determination. The receiving device determines the DMRS ports used and processes the retransmitted codewords based on the determination.