How Recurring Deposit Interest Is Calculated and When an RD Makes Sense
You open a recurring deposit of Rs 5,000 per month for 2 years. The bank quotes a 7% interest rate. At maturity, you expect the interest to be roughly 7% of your total deposits, but the actual number is lower, and for a mathematical reason, not because the bank is short‑changing you. Here is exactly how Indian banks calculate RD interest, how tax takes a bite, and when an RD is a better choice than a fixed deposit or a mutual fund SIP. This is for informational purposes only and is not financial advice.
Why RD interest is lower than FD interest at the same rate
In a fixed deposit, the entire principal sits in the account for the full tenure, earning interest every quarter. In a recurring deposit, only the first month's instalment stays for the full tenure. The second instalment stays for one month less, the third for two months less, and so on. The final instalment earns interest for only one month. So even though the bank quotes the same annual rate and compounds quarterly, the effective interest earned is lower because each deposit has less time to grow.
The formula Indian banks use for RD maturity is:
Maturity Amount = P × [ (1 + i)^(n) – 1 ] / [ 1 – (1 + i)^(–1/3) ]
Where P is the monthly deposit, i is the quarterly interest rate (annual rate divided by 4 and by 100), and n is the total number of quarters. This formula accounts for each monthly instalment earning interest only for the quarters it remains deposited.
Take a real example: Rs 5,000 per month for 2 years at 7% annual interest. Total deposits = Rs 1,20,000. The maturity amount from the formula is roughly Rs 1,29,100. Total interest = Rs 9,100. If this same Rs 1,20,000 were put in a 2‑year FD at 7% quarterly compounding, it would earn about Rs 17,800 in interest, nearly double. The reason is the staggered entry of money in the RD. Open the RD calculator, enter your monthly deposit and the bank's rate, and it applies this formula inside your browser. Your deposit details never leave your device.
RD vs FD vs SIP: which one for what goal
An RD works best when you do not have a lump sum and want a guaranteed return with zero risk. It is ideal for saving for a purchase 1–3 years away, a phone, a bike down payment, or a wedding expense. The return is fixed and the money is safe.
An FD works best when you already have a lump sum and want the same guaranteed return. Because the entire amount compounds from day one, the total interest earned is higher for the same rate and tenure.
A mutual fund SIP works for long‑term wealth building (5+ years) where you are willing to accept market risk in exchange for potentially higher returns. Historically, equity SIPs have delivered 10–12% over long periods, but there is no guarantee. An RD's return is lower but certain. For an emergency fund that must be absolutely safe, an RD or a liquid fund is better than an SIP.
How tax reduces your RD returns
RD interest is fully taxable, just like FD interest. The bank deducts TDS at 10% if the total interest earned across your RDs with that bank exceeds Rs 40,000 in a financial year (Rs 50,000 for senior citizens). If your PAN is not on file, TDS is 20%. The TDS is an advance tax; your final liability depends on your income slab. If you fall in the 20% slab, you will owe additional tax when filing your return. The calculator shows gross interest before TDS and tax. For the after‑tax number, reduce the interest by your slab rate. A tax professional can help with your specific calculation.
FAQ
Can I change the monthly deposit amount mid‑tenure?
No. The monthly deposit amount is fixed at the time of opening the RD. You cannot increase or decrease it. If you want to save a different amount, you need to open a separate RD or use a flexible savings option like a sweep‑in FD or a liquid mutual fund.
Does the calculator work for a 5‑year Post Office RD?
Yes. The Post Office recurring deposit uses the same quarterly compounding formula. The current interest rate is set by the Ministry of Finance and revised quarterly. Enter the rate, a monthly deposit, and 5 years as the tenure. The maturity amount shown will match the Post Office's official figure for that rate.
What happens if I miss a monthly instalment?
The bank usually charges a small penalty, often Rs 1.50 to Rs 2 per Rs 100 of the missed deposit per month. If you miss several instalments, the account may be discontinued. The penalty reduces your effective return. The calculator assumes all instalments are made on time. To keep the full projected return, set up a standing instruction to auto‑debit the RD amount each month.