This disclosure relates transform configuration and signaling for a compound inter-intra prediction modes. In one example, a method for decoding a video block in a video stream is disclosed. The method may include determining that the current block is predicted under a CIIP mode; generating a set of secondary transform coefficients for the current block from the video bitstream; applying a combined inter intra secondary transform by: performing an inverse separable or non-separable secondary transform on the set of secondary transform coefficients to obtain a set of primary transform coefficients of the current block; and performing an inverse primary transform on the set of primary transform coefficients to obtain a residual block of the current block; and decoding, under the CIIP mode, the current block from the residual block.