When do Defence Bonds pay a bonus? After 7 years they pay a bonus of £1 for every £100 invested. What interest do Defence Bonds pay? 3% per annum, which is paid half-yearly, May 1st and November 1st. Income Tax is not deducted at source. What are their other points? They never fluctuate in value. You can cash them at six months' notice, or in case of private emergency, you can apply to the Savings Bank at which your bonds are registered for repayment of the purchase price, subject to a deduction equal to six months' interest.