section 2.1 The components of "I" include miscellaneous income e.g. reinsurance income. Would that include reinsurance claims paid to the insurer? I cannot think of any other income from the reinsurer.
No - it is defined (for taxation purposes) as the investment return on reserves passed to the reinsurer. This is explained in more detail at the top of page 7 in Chapter 6 of the course notes.