Bond Index Remark : 1. The base date is 1 September 2006. 2. The net total return indices are calculated by applying the withholding tax rates to accrued interest and coupon payments on all coupon bonds. The tax rates may change from time to time due to changes to the withholding tax rate applicable in Thailand. The current and historical withholding tax rate is 15%. 3. The base date of the net total return indices is 20 August 2019. 4. For the manual of MTM Corporate Bond Index , please click here.