Charitable purpose registration: exceeding commercial receipts threshold denies exemption for the year but cancellation not mandatory. Where receipts from commercial activities exceed the proviso threshold in a particular year, the institution's income is not exempt for that year, but temporary excess alone does not mandate cancellation of registration if there is no change in the nature of activities; cancellation must follow statutory grounds and procedures, and unjustified cancellation may attract tax on accreted income under Chapter XII EB.