Most Indians treating PPF as a "tax-saving investment" park a ₹1.5 lakh deposit on March 31 every year, right before the financial-year cut-off. It works for the Section 80C deduction. But it costs money — because PPF interest is calculated on the lowest balance between the 5th and last day of every month.
Money deposited on March 31 earns zero interest for eleven months of that year. Money deposited on April 1–5 earns interest for the full year.
This is why the smart setup is: PPF calculator HDFC → monthly auto-debit → deposit before the 5th. Here is exactly how to do it, and what it saves.
Step 1: Use the PPF calculator HDFC-style to model your yearly commitment
PPF has one central-government-set rate (7.10% currently), so the maturity math is the same whether the account is with HDFC, SBI, ICICI or Post Office. A PPF calculator HDFC customer uses gives the same maturity number as any other bank's calculator.
What matters is picking the right yearly deposit amount for you:
| Yearly Deposit | Monthly Auto-Debit | 15-Year Maturity |
|---|---|---|
| ₹12,000 | ₹1,000 | ₹3.25 lakh |
| ₹60,000 | ₹5,000 | ₹16.28 lakh |
| ₹1,20,000 | ₹10,000 | ₹32.55 lakh |
| ₹1,50,000 (max) | ₹12,500 | ₹40.68 lakh |
Model your own number in our PPF calculator — enter any monthly commitment, and it shows the 15-year corpus at 7.10%, plus the tax saved under Section 80C.
Step 2: Set up the HDFC monthly auto-debit standing instruction
From your HDFC NetBanking:
- Log in → Funds Transfer → Standing Instructions.
- Beneficiary: your own PPF account (linked as an "own account transfer").
- Amount: your monthly figure from Step 1.
- Frequency: Monthly. Start date: 1st of the month.
- End date: 15 years from today (or set an indefinite instruction — you can cancel any time).
On the HDFC MobileBanking app, the same flow is under Pay → Standing Instruction. Takes about 5 minutes.
The math: monthly auto-debit vs March 31 lump deposit
At 7.10% over 15 years, on a ₹1.5 lakh annual commitment:
| Deposit Pattern | Total Invested | Maturity | Interest |
|---|---|---|---|
| Monthly on the 1st (₹12,500) | ₹22.50 L | ~₹40.68 L | ~₹18.18 L |
| Lump on Apr 1 (₹1,50,000) | ₹22.50 L | ~₹40.68 L | ~₹18.18 L |
| Lump on Mar 31 (₹1,50,000) | ₹22.50 L | ~₹39.34 L | ~₹16.84 L |
The March 31 pattern loses roughly ₹1.34 lakh of interest over 15 years, compared to disciplined monthly deposits. Not enormous — but it is completely free money you are leaving behind by clicking a payment 5 minutes later than needed.
Common mistakes to avoid
- Depositing more than ₹1.5 lakh in a financial year: anything above ₹1.5L earns zero interest and no 80C benefit.
- Missing a monthly deposit: no penalty, but you break your compounding rhythm. Set the standing instruction so this can't happen.
- Deposits after the 5th: that month's interest is lost. Auto-debit on the 1st avoids this entirely.
- Multiple PPF accounts: illegal. You can only have one PPF account across all banks/post offices in your name.
What about HDFC's PPF calculator on their app?
HDFC's in-app PPF calculator gives you the maturity number for a given yearly contribution — same as our PPF calculator. Neither shows you the "monthly-vs-lump" delta above. That is a decision you make about when to deposit, and it belongs in your calendar (or your auto-debit), not in the calculator.
Set the standing instruction. Model the corpus in a PPF calculator once. Forget about it for 15 years.