PPF Deposit Timing: The April 1-5 Rule That Costs You Real Money

Two people open a PPF account on the same day, put in the same ₹1.5 lakh every year for 15 years, and earn the same 7.1% rate. One ends up with roughly ₹2.7 lakh more than the other. Neither picked a better fund, took more risk, or timed the market. One just deposited early in the financial year and the other deposited late. That is the entire difference, and it comes down to a rule most PPF holders have never actually read.

PPF interest is not calculated on your average balance or your closing balance. It is calculated on the lowest balance in the account between the close of the 5th day of the month and the last day of the month, for every month, and credited once a year on 31 March. That single sentence in the PPF scheme rules is where the money is won or lost. This post works the actual arithmetic: what a late deposit costs, why “April 1 to 5” is the deadline everyone quotes, and the deposit calendar that captures every rupee of interest you are entitled to.

The rule, in plain terms

For each calendar month, the interest-earning balance is the smallest amount your account holds between the end of the 5th and the end of the month. So:

• Deposit on or before the 5th, and that money is part of the balance for the whole window. It earns interest for that month.
• Deposit on the 6th or later, and the balance on the 5th did not include it. The month’s minimum is the old, lower figure. Your fresh deposit earns nothing that month. It only starts earning from the next month.

A worked example. Your PPF has ₹10 lakh sitting in it. On 6 April you add ₹1.5 lakh, taking it to ₹11.5 lakh.

Balance on 5th April (close)   = ₹10,00,000
Balance on 30th April          = ₹11,50,000
Minimum between 5th and month-end = ₹10,00,000
April interest is paid on       ₹10,00,000, not ₹11,50,000

Your ₹1.5 lakh sat in the account for 24 days in April and earned zero interest for the month. Had you deposited it on 4 April instead, the April minimum would have been ₹11.5 lakh and the whole tranche would have earned. Two days on the calendar, one full month of interest.

The claim you will hear, and what is actually true

The popular version of this rule, repeated on every finance reel, is “deposit after the 5th and you lose a whole year of interest.” That is an exaggeration. On a single tranche in a single year, missing the 5 April window costs you one month of interest, not twelve. April is gone; May through March still pay.

But do not relax. Two things are true at once: the per-year loss is one month, and that one month, repeated across a 15-year account and left to compound, is real money. And the genuine “lose a year” mistake, depositing near the end of the financial year instead of the start, is far more expensive than the April 5 slip. Let us price all three.

What one month is worth: April 6 vs April 5

One month of interest on ₹1.5 lakh at 7.1%:

₹1,50,000 x 7.1% / 12 = ₹887.50

That is the first-year gap between depositing on 5 April and 6 April. It looks trivial. But that ₹887.50 shortfall is baked into your balance at the end of year one, and then it compounds at 7.1% for the remaining years of the account. Do it every single year for 15 years and each year’s lost ₹887.50 compounds for however long is left.

Summing the missed month across all 15 tranches, each compounded to maturity at 7.1%:

Total lost at maturity = ₹887.50 x [(1.071^15 - 1) / 0.071]
                       = ₹887.50 x 25.32
                       ≈ ₹22,470

So the habit of depositing on the 6th instead of the 5th, sustained for a full PPF tenure, quietly removes about ₹22,500 from your maturity corpus. Not life-changing, but it is a pure paperwork loss. You took no risk and did no work to lose it.

The expensive version: early vs late in the year

Now the mistake that actually deserves the “full year” label. Many people treat PPF as a March scramble, funding it just before the financial year closes to claim the Section 80C deduction. A deposit made in late March, after the 5th, earns essentially zero interest for that entire financial year. Compare that to funding it on 1 April: the same rupees earn a full 12 months.

The per-year gap here is the whole year’s interest on the tranche:

₹1,50,000 x 7.1% = ₹10,650 in year one

Repeat that pattern for 15 years and compound each shortfall to maturity. The math is clean, because depositing at year-end turns your PPF into an ordinary annuity while depositing at year-start makes it an annuity-due. The difference between the two over 15 years:

Figures assume a constant 7.1% for all 15 years, which will not hold in practice (the rate is reset quarterly), but the ranking and the rough magnitudes do hold. The person funding on 1 April walks away with ₹2.7 lakh more than the year-end funder, on identical contributions and identical rate. That is the real headline, and it dwarfs the April 5 slip.

Lump sum in April beats monthly, in PPF specifically

Notice the third row above. For a fixed-rate instrument like PPF, spreading ₹1.5 lakh across 12 monthly installments is worse than a single lump sum on 1 April, and this is the opposite of the advice you have heard for equity SIPs.

The reason: in equity, a SIP is about averaging out an unknown, volatile price. PPF has no price and no volatility. The rate is fixed and known. Every rupee you can get into the account earlier earns for longer. So the “rupee cost averaging” logic simply does not apply.

The month-by-month gap:

Lump sum, 1 April:     ₹1,50,000 earns 12 months = ₹10,650
12 monthly installments (each by 5th):
  April earns 12 months, May 11, ..., March 1
  Interest = ₹12,500 x 7.1%/12 x (12+11+...+1)
           = ₹12,500 x 7.1%/12 x 78
           ≈ ₹5,769

The monthly route earns barely more than half the first-year interest of the lump sum. Compounded across 15 years, that gap is about ₹1.24 lakh. If you have the ₹1.5 lakh available in April, deploy it in April. Only split into monthly deposits if your cash flow genuinely forces it, and even then, always land each installment by the 5th.

The deposit calendar, spelled out

Here is what your ₹1.5 lakh earns in its first financial year depending on when it lands, on the same 7.1% and the same 5th-of-month rule:

Every month you delay is worth ₹887.50 of that year’s interest walking out the door. There is no upside to waiting: the tax deduction under Section 80C is the same whether you deposit in April or March, and PPF interest is fully tax-free either way, so the only variable you control is time in the account. The optimal move is unambiguous.

The one date that matters

Deposit your full ₹1.5 lakh so that it credits to the PPF account on or before 5 April of each financial year. Not “in April.” On or before the 5th.

A practical caveat on the word “credits.” What counts is the date the money actually reaches the PPF account, not the date you initiate the transfer.

• NEFT, IMPS, UPI or an internal bank transfer to a PPF account with the same bank credits the same day. Doing it on 5 April is fine.
• A cheque credits on its clearing date, not the deposit date. Drop a cheque on the 5th and it may clear on the 7th, and you have missed the window. If you must use a cheque, deposit it by 1 or 2 April.
• For PPF accounts held at a different bank or the post office, allow a day or two for the transfer to settle. Aim for 1 to 3 April, not the 5th on the nose.

Set a recurring reminder for 1 April. Treat it like an EMI. This is the rare piece of financial optimization that takes five minutes once a year and needs zero judgment about markets.

Edge cases worth knowing

You cannot exceed ₹1.5 lakh in a year. The cap is a hard limit; excess deposits earn no interest and are returned without interest. So the game is entirely about timing the ₹1.5 lakh, not size.

Extension years work the same way. After 15 years you can extend in 5-year blocks, with or without fresh contributions. If you keep contributing, the 5 April rule keeps applying, and by now your balance is large, so the monthly interest at stake is bigger than ever.

The rate is not fixed for 15 years. PPF is reset every quarter by the government. It has drifted down from double digits in the 1990s to 7.1% today. The 7.1% in this post is the current rate used to illustrate the timing effect; the timing advantage exists at any rate, and is proportionally larger when rates are higher.

One financial year, one deadline. The 5 April rule is really the 5th-of-every-month rule. April simply happens to be the first and most valuable month, because a deposit that lands by 5 April captures all 12 months. That is why the whole conversation collapses to a single date.

Bottom line

Do this: transfer your full ₹1.5 lakh into PPF by 5 April every year, using an instant transfer (NEFT/IMPS/UPI) so it credits the same day, or a couple of days earlier if a cheque or an inter-bank transfer is involved. If cash flow forces monthly deposits, still land each one by the 5th, but lump sum in April is the better play for a fixed-rate product.

The stakes, on identical contributions and rate over 15 years: roughly ₹22,500 lost by slipping from 5 April to 6 April, about ₹1.24 lakh lost by dribbling it in monthly, and around ₹2.7 lakh lost by treating PPF as a March tax-season chore. None of that is compensation for risk or effort. It is money left on the table by not reading one line of the scheme rules.

Figures here are illustrative, assume a flat 7.1% that will in reality be revised quarterly, and are not investment advice. Verify the current rate and the crediting timeline for your specific bank before you deposit.