Deposit insurance requirement: companies must secure deposit insurance and insurers to cover principal and interest on default. Prior to its omission, Rule 5 required eligible companies inviting deposits to enter into a deposit insurance contract at least thirty days before issuing deposit offers or renewals; the contract fixed insurer liability for repayment of principal and interest up to an aggregate monetary ceiling with minimum protection for small deposits; the company bore the insurance premium and could not recover it from depositors; if non compliance made cover ineffective the company had to rectify or re-contract within thirty days or repay covered deposits and interest within fifteen days, with prescribed interest for delay and penal consequences.