Techniques for reporting channel state information (CSI) are disclosed. A user equipment (UE) may be configured for operation on multiple carriers with different configurations, e.g., FDD and TDD carriers and/or carriers with different uplink-downlink configurations. The multiple carriers may have different subframes for making measurements for CSI and/or different subframes for sending CSI. In response to a CSI request, the UE may determine at least one reference subframe to use for determining CSI for the multiple carriers. The reference subframe may be common to the plurality of carriers and may, for example, be based the subframe in which the CSI request in sent. Alternatively, the reference subframe may be different for different carriers such as when it is based on different HARQ timelines applicable for the different carriers. The UE may determine the CSI for the multiple carriers based on the reference subframe(s) and may report the CSI.