You may end up with getting lower coupon rate than specified if your investment exceeds ₹10 lakh in certain tax-free bonds. The benefit of higher interest rates in these bonds is offered only to retail investors for up to ₹10 lakh. In every tranche issued after FY14, issuers offered 25-30 bps higher coupon rates to retail investors. If any investment exceeds ₹10 lakh face value, then the bond buyer will lose the 25-30 bps in coupon rate. The limit applies to all series in a tranche, and to tax-free bonds in the secondary market. The investment value is calculated based on the PAN of the investor.