Tax-Free Bonds: Tax-free bonds are also a type of fixed-income option, where the interest received is tax-free. This is a type of debt investment. These bonds are usually issued by public sector undertakings or government-backed companies. These include NTPC, NHPC, India Infrastructure Finance Company Limited (IIFCL), National Highway Authority of India (NHAI), Housing and Urban Development Corporation Limited (HUDCO), Indian Railway Finance Corporation Limited (IRFC), Power Finance Corporation Limited (PFC), Companies like REC, NABARD are also included.