Master the PPF 5th-day rule for returns

• PPF interest rate held at 7.1% for Oct-Dec 2026 quarter
• Deposits made after the 5th of a month miss that month's interest
• Investors should deposit by the 5th to maximise annual returns

The Public Provident Fund (PPF) is a cornerstone of long-term savings for many Indians, prized for its safety and tax benefits. While the 7.1% interest rate offers stability, many investors are unaware of how this interest is actually calculated and applied.

The Steady 7.1% Interest Rate

The Ministry of Finance reviews the interest rates for small savings schemes, including the PPF, on a quarterly basis. For the quarter of October to December 2026, the rate has been held at 7.1% per annum, continuing a period of stability for the popular scheme. This consistency makes it an excellent time to understand the mechanics of how your investment grows, as the only variable you can control is your deposit strategy. While the interest is compounded and credited to your account annually on March 31st, the actual calculation happens every single month. This monthly calculation is where the details become crucial for maximising your returns.

The Secret Is in the Monthly Calculation

Here is the most important rule for any PPF investor: interest for any given month is calculated on the lowest balance held in the account between the close of the 5th day and the last day of that month. This means any deposit you make after the 5th of a month will not earn any interest for that entire month. It will only start earning interest from the following month. For example, if your account has a balance of ₹1,00,000 on April 1st and you deposit an additional ₹10,000 on April 6th, the interest for April will only be calculated on the minimum balance of ₹1,00,000, not the new total of ₹1,10,000. You effectively lose a month's worth of interest on that new deposit.

A Tale of Two Deposits: A Simple Example

Let’s see how this plays out. Imagine two friends, Priya and Rohan, both investing in PPF. On April 4th, Priya deposits ₹50,000 into her account. Because she made the deposit before the 5th, her contribution is included in the balance for April's interest calculation. Rohan makes the same ₹50,000 deposit but does so on April 7th. His deposit misses the cutoff. For the month of April, Priya earns interest on her ₹50,000, while Rohan earns nothing on his. His deposit will only be included in the calculation from May onwards. While a single month's interest may seem small, this effect accumulates significantly over the 15-year tenure of the PPF account, thanks to the power of annual compounding.

How to Maximise Your PPF Returns

Understanding the 'Rule of 5' gives you a clear strategy to make your money work harder. If you invest through monthly contributions, ensure your deposit is credited to your PPF account on or before the 5th of each month. Setting up an automated bank transfer for the 1st or 2nd of the month is a simple way to ensure you never miss this deadline. For those who prefer to invest a lump sum, the most effective strategy is to deposit the entire amount for the financial year before April 5th. By doing this, your investment earns interest for all 12 months of the financial year. A lump sum deposit of ₹1.5 lakh made before April 5th earns ₹10,650 in interest for the year at a 7.1% rate. If that same deposit is made after April 5th, it only earns interest for 11 months, resulting in an earning of just ₹9,762.50—a loss of nearly ₹900 in a single year.