I've been looking "tax-efficient" investing nowadays because ...well, why not? I saw too many variations to keep straight. So I created this table, which maybe useful for you too. This is based on secondary research. I discovered (which was a pleasant surprise) that listed NCDs, bonds including G-secs are treated on par with equity for taxation, which means it is only a one year holding period before you can claim long term gains!!! I also found conflicting opinions on Soverign Gold Bonds,where most articles said 3 years was the holding threshold , but others said 1 year since these were bonds and "listed", and hence qualified for 1 year. I erred on the side of caution a.k.a what ICICI direct and Zerodha said:). This is only for resident Indians.
So here is the table, in an image form. I will update if there are corrections/ other things to be added.
*Bonds: 1. When bonds that are purchased and redeemable at par are held till maturity then no capital gain shall arise on redemption.
2. Source: https://www1.nseindia.com/products/content/debt/ncbp/Taxation_of_Government_Securities.pdf
**SGB:
2. SGB are exempt from long term capital gain tax when held to maturity regardless of whether purchased at IPO or secondary market. I am unable to clearly identify tax treatment when bought and held for less than a 3 year period to redemption.