The PPF Rule That Costs Latecomers Thousands
Two accounts, identical deposits, identical rate — and one ends up materially poorer because of which day of the month the money arrived.
The 5th of the month rule
PPF interest each month is calculated on the lowest balance between the close of the 5th and the last day of that month. Deposit on the 4th and the money earns for the full month. Deposit on the 6th and it earns nothing until the following month.
One month of lost interest sounds trivial. Repeated for fifteen years on a maximum contribution, and with the forgone interest itself never compounding, it becomes a real number — the calculator quantifies it above.
The practical rule: deposit before the 5th of April for the whole year, or before the 5th of each month if spreading. April is optimal for a lump sum because it earns for all twelve months of the financial year.
Monthly interest basis
Interest = min(balance from 5th to month end) × rate ÷ 12
- A deposit after the 5th does not raise the minimum for that month
- Interest is credited once, at the end of the financial year
Lump sum in April versus spreading monthly
Depositing the full amount in April earns interest on the whole sum for twelve months. Spreading it across the year means each instalment earns for fewer months, so the annual interest is lower.
April is therefore better if you have the cash. Monthly is better than not contributing because the lump sum was unaffordable — switch the pattern above and compare rather than taking it on faith.
Loans and partial withdrawals
PPF locks money up for fifteen years, but not absolutely. From year 3 to year 6 you may borrow up to 25% of the balance at the end of the second preceding year, repayable with interest. From year 7 partial withdrawals are permitted, limited to 50% of the balance at the end of the fourth preceding year.
The ledger above shows both limits for every year, which is useful when deciding whether PPF can serve as a partial emergency reserve or should be treated as fully locked.
Why the tax status matters more than the rate
PPF is EEE: contributions are deductible under Section 80C, interest accrues tax-free, and maturity proceeds are tax-free. Nothing is taxed at any stage.
That makes the headline rate misleadingly low in comparison to taxable alternatives. A taxable deposit must earn substantially more before tax to match a tax-free PPF return for anyone in a higher slab — which is the real argument for the scheme, and it holds even when the notified rate looks unexciting.