This disclosure describes techniques for coding transform coefficients for a block of video data. According to these techniques, a video coder (a video encoder or video decoder) determines whether a block of video data is a luma block or a chroma block. If the block of video data is a luma block, the video coder adaptively updates a VLC table index value based on a code number cn and value of a scaling factor. However, if the block of video data is a chroma block, the video coder adaptively updates the VLC table index value based on the code number cn and without using the scaling factor. The video coder uses the updated VLC table index value to select a VLC table of a plurality of VLC tables that are used to encode or decode the block of video data.