Corpus investment requirement: voluntary contributions must be deposited in prescribed modes to qualify as application of income. Voluntary contributions to a trust or institution's corpus will be treated as application of income only if invested or deposited in prescribed forms or modes maintained specifically for that corpus; disbursements from corpus or from loans are not treated as application of income until amounts are reinvested into those prescribed forms or until loans are repaid from income in a later year. Calculation of income required to be applied or accumulated for the previous year must be made without set off or allowance for any excess application from earlier years. Cross references to registration/approval provisions are expanded in related sub sections.