PPF, Senior Citizen Savings Scheme, and Sukanya Samriddhi Account: Interest rates of small savings schemes are due for revision at the end of this month. The interest rates of small savings schemes are linked to yields of 10-year Government Securities in the secondary market. There are set formulae for mark-ups over the previous three months average yield of relevant G-Secs of comparable maturity. Let's see if you are in for a New Year bonanza from the Central Government this time.