Banks generally offer either of the following loan options: Floating Rate Home Loans and Fixed Rate Home Loans. For a Fixed Rate Loan, the rate of interest is fixed either for the entire tenure of the loan or a certain part of the tenure of the loan. In case of a pure fixed loan, the EMI due to the bank remains constant. If a bank offers a Loan which is fixed only for a certain period of the tenure of the loan, please try to elicit information from the bank whether the rates may be raised after the period (reset clause). You may try to negotiate a lock-in that should include the rate that you have agreed upon initially and the period the lock-in lasts.
Hence, the EMI of a fixed rate loan is known in advance. This is the cash outflow that can be planned for at the outset of the loan. If the inflation and the interest rate in the economy move up over the years, a fixed EMI is attractively stagnant and is easier to plan for. However, if you have fixed EMI, any reduction in interest rates in the market, will not benefit you.
Determinants of floating rate:
The EMI of a floating rate loan changes with changes in market interest rates. If market rates increase, your repayment increases. When rates fall, your dues also fall. The floating interest rate is made up of two parts: the index and the spread. The index is a measure of interest rates generally (based on say, government securities prices), and the spread is an extra amount that the banker adds to cover credit risk, profit mark-up etc. The amount of the spread may differ from one lender to another, but it is usually constant over the life of the loan. If the index rate moves up, so does your interest rate in most circumstances and you will have to pay a higher EMI. Conversely, if the interest rate moves down, your EMI amount should be lower.
Also, sometimes banks make some adjustments so that your EMI remains constant. In such cases, when a lender increases the floating interest rate, the tenure of the loan is increased (and EMI kept constant).
Some lenders also base their floating rates on their Benchmark Prime Lending Rates (BPLR). You should ask what index will be used for setting the floating rate, how it has generally fluctuated in the past, and where it is published/disclosed. However, the past fluctuation of any index is not a guarantee for its future behavior.