How do I check the interest payment schedule for my G-sec investments?
The interest payments for dated Govt. bonds are made semi-annually from the date of issue.
For example - If date of issue is January 8, 2018 - the coupon payment dates will be Half-yearly (July 08 and January 08) every year until maturity.
The interest payment dates can also be found on the RBI notifications page. You can find them on notifications titled - "Auction for Sale (Issue/Re-issue) of Government Stock (GS)"
For older issues, you'll be able to find the Auction for Sale (Re-issue) of Government Stock (GS) document under Archives.