Most trust funds will have some permanent capital - the original endowment that cannot be spent by the Managers. A number of funds do not have permanent capital as, under the terms of the bequest, both the original donation and any income generated, may be spent.

The permanent capital of a trust fund is invested in the Cambridge University Endowment Fund (CUEF) and is treated as a long-term investment, i.e. the units held cannot be sold. The CUEF income generated from the permanent capital is credited monthly to the spendable part of a Trust Fund (cost centre ZZYB) under the transaction code NAAA.