Company FDs are unsecured investments that offer a fixed return. Corporate FDs pay higher interest than bank FDs, usually 0.75 per cent to 1.5 per cent higher. Senior citizens can even earn additional interest rates of 0.25 per cent to 0.5 per cent, depending on the company. At present, many AAA-rated company FDs offer interest rates of more than 8 per cent. So, what factors you should keep in mind while investing in corporate FDs. ET Wealth explains