National saving certificate (NSC) is a tax saving instrument. It is one of the most popular vehicle for tax savings. Hence any investment into this is eligible for tax deduction. The investment comes under section 80C. You can buy NSC from any head post office.
The tenure of investment is 5 and 10 years and the interest earned is 8.6%.
The interest accrued is taxable unless you declare it within the limit of 80C. It is a good practice to declare the interest earned every year and claim tax deduction on it under 80C. If you do not do this, the interest will be taxed at the time of maturity.